Loading...
1/*
2 * mm/rmap.c - physical to virtual reverse mappings
3 *
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL).
6 *
7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible.
9 *
10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode.
13 *
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins 2003, 2004
18 */
19
20/*
21 * Lock ordering in mm:
22 *
23 * inode->i_rwsem (while writing or truncating, not reading or faulting)
24 * mm->mmap_lock
25 * mapping->invalidate_lock (in filemap_fault)
26 * page->flags PG_locked (lock_page)
27 * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share, see hugetlbfs below)
28 * vma_start_write
29 * mapping->i_mmap_rwsem
30 * anon_vma->rwsem
31 * mm->page_table_lock or pte_lock
32 * swap_lock (in swap_duplicate, swap_info_get)
33 * mmlist_lock (in mmput, drain_mmlist and others)
34 * mapping->private_lock (in block_dirty_folio)
35 * folio_lock_memcg move_lock (in block_dirty_folio)
36 * i_pages lock (widely used)
37 * lruvec->lru_lock (in folio_lruvec_lock_irq)
38 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
39 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
40 * sb_lock (within inode_lock in fs/fs-writeback.c)
41 * i_pages lock (widely used, in set_page_dirty,
42 * in arch-dependent flush_dcache_mmap_lock,
43 * within bdi.wb->list_lock in __sync_single_inode)
44 *
45 * anon_vma->rwsem,mapping->i_mmap_rwsem (memory_failure, collect_procs_anon)
46 * ->tasklist_lock
47 * pte map lock
48 *
49 * hugetlbfs PageHuge() take locks in this order:
50 * hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
51 * vma_lock (hugetlb specific lock for pmd_sharing)
52 * mapping->i_mmap_rwsem (also used for hugetlb pmd sharing)
53 * page->flags PG_locked (lock_page)
54 */
55
56#include <linux/mm.h>
57#include <linux/sched/mm.h>
58#include <linux/sched/task.h>
59#include <linux/pagemap.h>
60#include <linux/swap.h>
61#include <linux/swapops.h>
62#include <linux/slab.h>
63#include <linux/init.h>
64#include <linux/ksm.h>
65#include <linux/rmap.h>
66#include <linux/rcupdate.h>
67#include <linux/export.h>
68#include <linux/memcontrol.h>
69#include <linux/mmu_notifier.h>
70#include <linux/migrate.h>
71#include <linux/hugetlb.h>
72#include <linux/huge_mm.h>
73#include <linux/backing-dev.h>
74#include <linux/page_idle.h>
75#include <linux/memremap.h>
76#include <linux/userfaultfd_k.h>
77#include <linux/mm_inline.h>
78
79#include <asm/tlbflush.h>
80
81#define CREATE_TRACE_POINTS
82#include <trace/events/tlb.h>
83#include <trace/events/migrate.h>
84
85#include "internal.h"
86
87static struct kmem_cache *anon_vma_cachep;
88static struct kmem_cache *anon_vma_chain_cachep;
89
90static inline struct anon_vma *anon_vma_alloc(void)
91{
92 struct anon_vma *anon_vma;
93
94 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
95 if (anon_vma) {
96 atomic_set(&anon_vma->refcount, 1);
97 anon_vma->num_children = 0;
98 anon_vma->num_active_vmas = 0;
99 anon_vma->parent = anon_vma;
100 /*
101 * Initialise the anon_vma root to point to itself. If called
102 * from fork, the root will be reset to the parents anon_vma.
103 */
104 anon_vma->root = anon_vma;
105 }
106
107 return anon_vma;
108}
109
110static inline void anon_vma_free(struct anon_vma *anon_vma)
111{
112 VM_BUG_ON(atomic_read(&anon_vma->refcount));
113
114 /*
115 * Synchronize against folio_lock_anon_vma_read() such that
116 * we can safely hold the lock without the anon_vma getting
117 * freed.
118 *
119 * Relies on the full mb implied by the atomic_dec_and_test() from
120 * put_anon_vma() against the acquire barrier implied by
121 * down_read_trylock() from folio_lock_anon_vma_read(). This orders:
122 *
123 * folio_lock_anon_vma_read() VS put_anon_vma()
124 * down_read_trylock() atomic_dec_and_test()
125 * LOCK MB
126 * atomic_read() rwsem_is_locked()
127 *
128 * LOCK should suffice since the actual taking of the lock must
129 * happen _before_ what follows.
130 */
131 might_sleep();
132 if (rwsem_is_locked(&anon_vma->root->rwsem)) {
133 anon_vma_lock_write(anon_vma);
134 anon_vma_unlock_write(anon_vma);
135 }
136
137 kmem_cache_free(anon_vma_cachep, anon_vma);
138}
139
140static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
141{
142 return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
143}
144
145static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
146{
147 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
148}
149
150static void anon_vma_chain_link(struct vm_area_struct *vma,
151 struct anon_vma_chain *avc,
152 struct anon_vma *anon_vma)
153{
154 avc->vma = vma;
155 avc->anon_vma = anon_vma;
156 list_add(&avc->same_vma, &vma->anon_vma_chain);
157 anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
158}
159
160/**
161 * __anon_vma_prepare - attach an anon_vma to a memory region
162 * @vma: the memory region in question
163 *
164 * This makes sure the memory mapping described by 'vma' has
165 * an 'anon_vma' attached to it, so that we can associate the
166 * anonymous pages mapped into it with that anon_vma.
167 *
168 * The common case will be that we already have one, which
169 * is handled inline by anon_vma_prepare(). But if
170 * not we either need to find an adjacent mapping that we
171 * can re-use the anon_vma from (very common when the only
172 * reason for splitting a vma has been mprotect()), or we
173 * allocate a new one.
174 *
175 * Anon-vma allocations are very subtle, because we may have
176 * optimistically looked up an anon_vma in folio_lock_anon_vma_read()
177 * and that may actually touch the rwsem even in the newly
178 * allocated vma (it depends on RCU to make sure that the
179 * anon_vma isn't actually destroyed).
180 *
181 * As a result, we need to do proper anon_vma locking even
182 * for the new allocation. At the same time, we do not want
183 * to do any locking for the common case of already having
184 * an anon_vma.
185 *
186 * This must be called with the mmap_lock held for reading.
187 */
188int __anon_vma_prepare(struct vm_area_struct *vma)
189{
190 struct mm_struct *mm = vma->vm_mm;
191 struct anon_vma *anon_vma, *allocated;
192 struct anon_vma_chain *avc;
193
194 might_sleep();
195
196 avc = anon_vma_chain_alloc(GFP_KERNEL);
197 if (!avc)
198 goto out_enomem;
199
200 anon_vma = find_mergeable_anon_vma(vma);
201 allocated = NULL;
202 if (!anon_vma) {
203 anon_vma = anon_vma_alloc();
204 if (unlikely(!anon_vma))
205 goto out_enomem_free_avc;
206 anon_vma->num_children++; /* self-parent link for new root */
207 allocated = anon_vma;
208 }
209
210 anon_vma_lock_write(anon_vma);
211 /* page_table_lock to protect against threads */
212 spin_lock(&mm->page_table_lock);
213 if (likely(!vma->anon_vma)) {
214 vma->anon_vma = anon_vma;
215 anon_vma_chain_link(vma, avc, anon_vma);
216 anon_vma->num_active_vmas++;
217 allocated = NULL;
218 avc = NULL;
219 }
220 spin_unlock(&mm->page_table_lock);
221 anon_vma_unlock_write(anon_vma);
222
223 if (unlikely(allocated))
224 put_anon_vma(allocated);
225 if (unlikely(avc))
226 anon_vma_chain_free(avc);
227
228 return 0;
229
230 out_enomem_free_avc:
231 anon_vma_chain_free(avc);
232 out_enomem:
233 return -ENOMEM;
234}
235
236/*
237 * This is a useful helper function for locking the anon_vma root as
238 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
239 * have the same vma.
240 *
241 * Such anon_vma's should have the same root, so you'd expect to see
242 * just a single mutex_lock for the whole traversal.
243 */
244static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
245{
246 struct anon_vma *new_root = anon_vma->root;
247 if (new_root != root) {
248 if (WARN_ON_ONCE(root))
249 up_write(&root->rwsem);
250 root = new_root;
251 down_write(&root->rwsem);
252 }
253 return root;
254}
255
256static inline void unlock_anon_vma_root(struct anon_vma *root)
257{
258 if (root)
259 up_write(&root->rwsem);
260}
261
262/*
263 * Attach the anon_vmas from src to dst.
264 * Returns 0 on success, -ENOMEM on failure.
265 *
266 * anon_vma_clone() is called by vma_expand(), vma_merge(), __split_vma(),
267 * copy_vma() and anon_vma_fork(). The first four want an exact copy of src,
268 * while the last one, anon_vma_fork(), may try to reuse an existing anon_vma to
269 * prevent endless growth of anon_vma. Since dst->anon_vma is set to NULL before
270 * call, we can identify this case by checking (!dst->anon_vma &&
271 * src->anon_vma).
272 *
273 * If (!dst->anon_vma && src->anon_vma) is true, this function tries to find
274 * and reuse existing anon_vma which has no vmas and only one child anon_vma.
275 * This prevents degradation of anon_vma hierarchy to endless linear chain in
276 * case of constantly forking task. On the other hand, an anon_vma with more
277 * than one child isn't reused even if there was no alive vma, thus rmap
278 * walker has a good chance of avoiding scanning the whole hierarchy when it
279 * searches where page is mapped.
280 */
281int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
282{
283 struct anon_vma_chain *avc, *pavc;
284 struct anon_vma *root = NULL;
285
286 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
287 struct anon_vma *anon_vma;
288
289 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
290 if (unlikely(!avc)) {
291 unlock_anon_vma_root(root);
292 root = NULL;
293 avc = anon_vma_chain_alloc(GFP_KERNEL);
294 if (!avc)
295 goto enomem_failure;
296 }
297 anon_vma = pavc->anon_vma;
298 root = lock_anon_vma_root(root, anon_vma);
299 anon_vma_chain_link(dst, avc, anon_vma);
300
301 /*
302 * Reuse existing anon_vma if it has no vma and only one
303 * anon_vma child.
304 *
305 * Root anon_vma is never reused:
306 * it has self-parent reference and at least one child.
307 */
308 if (!dst->anon_vma && src->anon_vma &&
309 anon_vma->num_children < 2 &&
310 anon_vma->num_active_vmas == 0)
311 dst->anon_vma = anon_vma;
312 }
313 if (dst->anon_vma)
314 dst->anon_vma->num_active_vmas++;
315 unlock_anon_vma_root(root);
316 return 0;
317
318 enomem_failure:
319 /*
320 * dst->anon_vma is dropped here otherwise its num_active_vmas can
321 * be incorrectly decremented in unlink_anon_vmas().
322 * We can safely do this because callers of anon_vma_clone() don't care
323 * about dst->anon_vma if anon_vma_clone() failed.
324 */
325 dst->anon_vma = NULL;
326 unlink_anon_vmas(dst);
327 return -ENOMEM;
328}
329
330/*
331 * Attach vma to its own anon_vma, as well as to the anon_vmas that
332 * the corresponding VMA in the parent process is attached to.
333 * Returns 0 on success, non-zero on failure.
334 */
335int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
336{
337 struct anon_vma_chain *avc;
338 struct anon_vma *anon_vma;
339 int error;
340
341 /* Don't bother if the parent process has no anon_vma here. */
342 if (!pvma->anon_vma)
343 return 0;
344
345 /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
346 vma->anon_vma = NULL;
347
348 /*
349 * First, attach the new VMA to the parent VMA's anon_vmas,
350 * so rmap can find non-COWed pages in child processes.
351 */
352 error = anon_vma_clone(vma, pvma);
353 if (error)
354 return error;
355
356 /* An existing anon_vma has been reused, all done then. */
357 if (vma->anon_vma)
358 return 0;
359
360 /* Then add our own anon_vma. */
361 anon_vma = anon_vma_alloc();
362 if (!anon_vma)
363 goto out_error;
364 anon_vma->num_active_vmas++;
365 avc = anon_vma_chain_alloc(GFP_KERNEL);
366 if (!avc)
367 goto out_error_free_anon_vma;
368
369 /*
370 * The root anon_vma's rwsem is the lock actually used when we
371 * lock any of the anon_vmas in this anon_vma tree.
372 */
373 anon_vma->root = pvma->anon_vma->root;
374 anon_vma->parent = pvma->anon_vma;
375 /*
376 * With refcounts, an anon_vma can stay around longer than the
377 * process it belongs to. The root anon_vma needs to be pinned until
378 * this anon_vma is freed, because the lock lives in the root.
379 */
380 get_anon_vma(anon_vma->root);
381 /* Mark this anon_vma as the one where our new (COWed) pages go. */
382 vma->anon_vma = anon_vma;
383 anon_vma_lock_write(anon_vma);
384 anon_vma_chain_link(vma, avc, anon_vma);
385 anon_vma->parent->num_children++;
386 anon_vma_unlock_write(anon_vma);
387
388 return 0;
389
390 out_error_free_anon_vma:
391 put_anon_vma(anon_vma);
392 out_error:
393 unlink_anon_vmas(vma);
394 return -ENOMEM;
395}
396
397void unlink_anon_vmas(struct vm_area_struct *vma)
398{
399 struct anon_vma_chain *avc, *next;
400 struct anon_vma *root = NULL;
401
402 /*
403 * Unlink each anon_vma chained to the VMA. This list is ordered
404 * from newest to oldest, ensuring the root anon_vma gets freed last.
405 */
406 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
407 struct anon_vma *anon_vma = avc->anon_vma;
408
409 root = lock_anon_vma_root(root, anon_vma);
410 anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
411
412 /*
413 * Leave empty anon_vmas on the list - we'll need
414 * to free them outside the lock.
415 */
416 if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) {
417 anon_vma->parent->num_children--;
418 continue;
419 }
420
421 list_del(&avc->same_vma);
422 anon_vma_chain_free(avc);
423 }
424 if (vma->anon_vma) {
425 vma->anon_vma->num_active_vmas--;
426
427 /*
428 * vma would still be needed after unlink, and anon_vma will be prepared
429 * when handle fault.
430 */
431 vma->anon_vma = NULL;
432 }
433 unlock_anon_vma_root(root);
434
435 /*
436 * Iterate the list once more, it now only contains empty and unlinked
437 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
438 * needing to write-acquire the anon_vma->root->rwsem.
439 */
440 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
441 struct anon_vma *anon_vma = avc->anon_vma;
442
443 VM_WARN_ON(anon_vma->num_children);
444 VM_WARN_ON(anon_vma->num_active_vmas);
445 put_anon_vma(anon_vma);
446
447 list_del(&avc->same_vma);
448 anon_vma_chain_free(avc);
449 }
450}
451
452static void anon_vma_ctor(void *data)
453{
454 struct anon_vma *anon_vma = data;
455
456 init_rwsem(&anon_vma->rwsem);
457 atomic_set(&anon_vma->refcount, 0);
458 anon_vma->rb_root = RB_ROOT_CACHED;
459}
460
461void __init anon_vma_init(void)
462{
463 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
464 0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
465 anon_vma_ctor);
466 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
467 SLAB_PANIC|SLAB_ACCOUNT);
468}
469
470/*
471 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
472 *
473 * Since there is no serialization what so ever against folio_remove_rmap_*()
474 * the best this function can do is return a refcount increased anon_vma
475 * that might have been relevant to this page.
476 *
477 * The page might have been remapped to a different anon_vma or the anon_vma
478 * returned may already be freed (and even reused).
479 *
480 * In case it was remapped to a different anon_vma, the new anon_vma will be a
481 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
482 * ensure that any anon_vma obtained from the page will still be valid for as
483 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
484 *
485 * All users of this function must be very careful when walking the anon_vma
486 * chain and verify that the page in question is indeed mapped in it
487 * [ something equivalent to page_mapped_in_vma() ].
488 *
489 * Since anon_vma's slab is SLAB_TYPESAFE_BY_RCU and we know from
490 * folio_remove_rmap_*() that the anon_vma pointer from page->mapping is valid
491 * if there is a mapcount, we can dereference the anon_vma after observing
492 * those.
493 *
494 * NOTE: the caller should normally hold folio lock when calling this. If
495 * not, the caller needs to double check the anon_vma didn't change after
496 * taking the anon_vma lock for either read or write (UFFDIO_MOVE can modify it
497 * concurrently without folio lock protection). See folio_lock_anon_vma_read()
498 * which has already covered that, and comment above remap_pages().
499 */
500struct anon_vma *folio_get_anon_vma(struct folio *folio)
501{
502 struct anon_vma *anon_vma = NULL;
503 unsigned long anon_mapping;
504
505 rcu_read_lock();
506 anon_mapping = (unsigned long)READ_ONCE(folio->mapping);
507 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
508 goto out;
509 if (!folio_mapped(folio))
510 goto out;
511
512 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
513 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
514 anon_vma = NULL;
515 goto out;
516 }
517
518 /*
519 * If this folio is still mapped, then its anon_vma cannot have been
520 * freed. But if it has been unmapped, we have no security against the
521 * anon_vma structure being freed and reused (for another anon_vma:
522 * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
523 * above cannot corrupt).
524 */
525 if (!folio_mapped(folio)) {
526 rcu_read_unlock();
527 put_anon_vma(anon_vma);
528 return NULL;
529 }
530out:
531 rcu_read_unlock();
532
533 return anon_vma;
534}
535
536/*
537 * Similar to folio_get_anon_vma() except it locks the anon_vma.
538 *
539 * Its a little more complex as it tries to keep the fast path to a single
540 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
541 * reference like with folio_get_anon_vma() and then block on the mutex
542 * on !rwc->try_lock case.
543 */
544struct anon_vma *folio_lock_anon_vma_read(struct folio *folio,
545 struct rmap_walk_control *rwc)
546{
547 struct anon_vma *anon_vma = NULL;
548 struct anon_vma *root_anon_vma;
549 unsigned long anon_mapping;
550
551retry:
552 rcu_read_lock();
553 anon_mapping = (unsigned long)READ_ONCE(folio->mapping);
554 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
555 goto out;
556 if (!folio_mapped(folio))
557 goto out;
558
559 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
560 root_anon_vma = READ_ONCE(anon_vma->root);
561 if (down_read_trylock(&root_anon_vma->rwsem)) {
562 /*
563 * folio_move_anon_rmap() might have changed the anon_vma as we
564 * might not hold the folio lock here.
565 */
566 if (unlikely((unsigned long)READ_ONCE(folio->mapping) !=
567 anon_mapping)) {
568 up_read(&root_anon_vma->rwsem);
569 rcu_read_unlock();
570 goto retry;
571 }
572
573 /*
574 * If the folio is still mapped, then this anon_vma is still
575 * its anon_vma, and holding the mutex ensures that it will
576 * not go away, see anon_vma_free().
577 */
578 if (!folio_mapped(folio)) {
579 up_read(&root_anon_vma->rwsem);
580 anon_vma = NULL;
581 }
582 goto out;
583 }
584
585 if (rwc && rwc->try_lock) {
586 anon_vma = NULL;
587 rwc->contended = true;
588 goto out;
589 }
590
591 /* trylock failed, we got to sleep */
592 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
593 anon_vma = NULL;
594 goto out;
595 }
596
597 if (!folio_mapped(folio)) {
598 rcu_read_unlock();
599 put_anon_vma(anon_vma);
600 return NULL;
601 }
602
603 /* we pinned the anon_vma, its safe to sleep */
604 rcu_read_unlock();
605 anon_vma_lock_read(anon_vma);
606
607 /*
608 * folio_move_anon_rmap() might have changed the anon_vma as we might
609 * not hold the folio lock here.
610 */
611 if (unlikely((unsigned long)READ_ONCE(folio->mapping) !=
612 anon_mapping)) {
613 anon_vma_unlock_read(anon_vma);
614 put_anon_vma(anon_vma);
615 anon_vma = NULL;
616 goto retry;
617 }
618
619 if (atomic_dec_and_test(&anon_vma->refcount)) {
620 /*
621 * Oops, we held the last refcount, release the lock
622 * and bail -- can't simply use put_anon_vma() because
623 * we'll deadlock on the anon_vma_lock_write() recursion.
624 */
625 anon_vma_unlock_read(anon_vma);
626 __put_anon_vma(anon_vma);
627 anon_vma = NULL;
628 }
629
630 return anon_vma;
631
632out:
633 rcu_read_unlock();
634 return anon_vma;
635}
636
637#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
638/*
639 * Flush TLB entries for recently unmapped pages from remote CPUs. It is
640 * important if a PTE was dirty when it was unmapped that it's flushed
641 * before any IO is initiated on the page to prevent lost writes. Similarly,
642 * it must be flushed before freeing to prevent data leakage.
643 */
644void try_to_unmap_flush(void)
645{
646 struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
647
648 if (!tlb_ubc->flush_required)
649 return;
650
651 arch_tlbbatch_flush(&tlb_ubc->arch);
652 tlb_ubc->flush_required = false;
653 tlb_ubc->writable = false;
654}
655
656/* Flush iff there are potentially writable TLB entries that can race with IO */
657void try_to_unmap_flush_dirty(void)
658{
659 struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
660
661 if (tlb_ubc->writable)
662 try_to_unmap_flush();
663}
664
665/*
666 * Bits 0-14 of mm->tlb_flush_batched record pending generations.
667 * Bits 16-30 of mm->tlb_flush_batched bit record flushed generations.
668 */
669#define TLB_FLUSH_BATCH_FLUSHED_SHIFT 16
670#define TLB_FLUSH_BATCH_PENDING_MASK \
671 ((1 << (TLB_FLUSH_BATCH_FLUSHED_SHIFT - 1)) - 1)
672#define TLB_FLUSH_BATCH_PENDING_LARGE \
673 (TLB_FLUSH_BATCH_PENDING_MASK / 2)
674
675static void set_tlb_ubc_flush_pending(struct mm_struct *mm, pte_t pteval,
676 unsigned long uaddr)
677{
678 struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
679 int batch;
680 bool writable = pte_dirty(pteval);
681
682 if (!pte_accessible(mm, pteval))
683 return;
684
685 arch_tlbbatch_add_pending(&tlb_ubc->arch, mm, uaddr);
686 tlb_ubc->flush_required = true;
687
688 /*
689 * Ensure compiler does not re-order the setting of tlb_flush_batched
690 * before the PTE is cleared.
691 */
692 barrier();
693 batch = atomic_read(&mm->tlb_flush_batched);
694retry:
695 if ((batch & TLB_FLUSH_BATCH_PENDING_MASK) > TLB_FLUSH_BATCH_PENDING_LARGE) {
696 /*
697 * Prevent `pending' from catching up with `flushed' because of
698 * overflow. Reset `pending' and `flushed' to be 1 and 0 if
699 * `pending' becomes large.
700 */
701 if (!atomic_try_cmpxchg(&mm->tlb_flush_batched, &batch, 1))
702 goto retry;
703 } else {
704 atomic_inc(&mm->tlb_flush_batched);
705 }
706
707 /*
708 * If the PTE was dirty then it's best to assume it's writable. The
709 * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
710 * before the page is queued for IO.
711 */
712 if (writable)
713 tlb_ubc->writable = true;
714}
715
716/*
717 * Returns true if the TLB flush should be deferred to the end of a batch of
718 * unmap operations to reduce IPIs.
719 */
720static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
721{
722 if (!(flags & TTU_BATCH_FLUSH))
723 return false;
724
725 return arch_tlbbatch_should_defer(mm);
726}
727
728/*
729 * Reclaim unmaps pages under the PTL but do not flush the TLB prior to
730 * releasing the PTL if TLB flushes are batched. It's possible for a parallel
731 * operation such as mprotect or munmap to race between reclaim unmapping
732 * the page and flushing the page. If this race occurs, it potentially allows
733 * access to data via a stale TLB entry. Tracking all mm's that have TLB
734 * batching in flight would be expensive during reclaim so instead track
735 * whether TLB batching occurred in the past and if so then do a flush here
736 * if required. This will cost one additional flush per reclaim cycle paid
737 * by the first operation at risk such as mprotect and mumap.
738 *
739 * This must be called under the PTL so that an access to tlb_flush_batched
740 * that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise
741 * via the PTL.
742 */
743void flush_tlb_batched_pending(struct mm_struct *mm)
744{
745 int batch = atomic_read(&mm->tlb_flush_batched);
746 int pending = batch & TLB_FLUSH_BATCH_PENDING_MASK;
747 int flushed = batch >> TLB_FLUSH_BATCH_FLUSHED_SHIFT;
748
749 if (pending != flushed) {
750 arch_flush_tlb_batched_pending(mm);
751 /*
752 * If the new TLB flushing is pending during flushing, leave
753 * mm->tlb_flush_batched as is, to avoid losing flushing.
754 */
755 atomic_cmpxchg(&mm->tlb_flush_batched, batch,
756 pending | (pending << TLB_FLUSH_BATCH_FLUSHED_SHIFT));
757 }
758}
759#else
760static void set_tlb_ubc_flush_pending(struct mm_struct *mm, pte_t pteval,
761 unsigned long uaddr)
762{
763}
764
765static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
766{
767 return false;
768}
769#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
770
771/*
772 * At what user virtual address is page expected in vma?
773 * Caller should check the page is actually part of the vma.
774 */
775unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
776{
777 struct folio *folio = page_folio(page);
778 if (folio_test_anon(folio)) {
779 struct anon_vma *page__anon_vma = folio_anon_vma(folio);
780 /*
781 * Note: swapoff's unuse_vma() is more efficient with this
782 * check, and needs it to match anon_vma when KSM is active.
783 */
784 if (!vma->anon_vma || !page__anon_vma ||
785 vma->anon_vma->root != page__anon_vma->root)
786 return -EFAULT;
787 } else if (!vma->vm_file) {
788 return -EFAULT;
789 } else if (vma->vm_file->f_mapping != folio->mapping) {
790 return -EFAULT;
791 }
792
793 return vma_address(page, vma);
794}
795
796/*
797 * Returns the actual pmd_t* where we expect 'address' to be mapped from, or
798 * NULL if it doesn't exist. No guarantees / checks on what the pmd_t*
799 * represents.
800 */
801pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
802{
803 pgd_t *pgd;
804 p4d_t *p4d;
805 pud_t *pud;
806 pmd_t *pmd = NULL;
807
808 pgd = pgd_offset(mm, address);
809 if (!pgd_present(*pgd))
810 goto out;
811
812 p4d = p4d_offset(pgd, address);
813 if (!p4d_present(*p4d))
814 goto out;
815
816 pud = pud_offset(p4d, address);
817 if (!pud_present(*pud))
818 goto out;
819
820 pmd = pmd_offset(pud, address);
821out:
822 return pmd;
823}
824
825struct folio_referenced_arg {
826 int mapcount;
827 int referenced;
828 unsigned long vm_flags;
829 struct mem_cgroup *memcg;
830};
831
832/*
833 * arg: folio_referenced_arg will be passed
834 */
835static bool folio_referenced_one(struct folio *folio,
836 struct vm_area_struct *vma, unsigned long address, void *arg)
837{
838 struct folio_referenced_arg *pra = arg;
839 DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
840 int referenced = 0;
841 unsigned long start = address, ptes = 0;
842
843 while (page_vma_mapped_walk(&pvmw)) {
844 address = pvmw.address;
845
846 if (vma->vm_flags & VM_LOCKED) {
847 if (!folio_test_large(folio) || !pvmw.pte) {
848 /* Restore the mlock which got missed */
849 mlock_vma_folio(folio, vma);
850 page_vma_mapped_walk_done(&pvmw);
851 pra->vm_flags |= VM_LOCKED;
852 return false; /* To break the loop */
853 }
854 /*
855 * For large folio fully mapped to VMA, will
856 * be handled after the pvmw loop.
857 *
858 * For large folio cross VMA boundaries, it's
859 * expected to be picked by page reclaim. But
860 * should skip reference of pages which are in
861 * the range of VM_LOCKED vma. As page reclaim
862 * should just count the reference of pages out
863 * the range of VM_LOCKED vma.
864 */
865 ptes++;
866 pra->mapcount--;
867 continue;
868 }
869
870 if (pvmw.pte) {
871 if (lru_gen_enabled() &&
872 pte_young(ptep_get(pvmw.pte))) {
873 lru_gen_look_around(&pvmw);
874 referenced++;
875 }
876
877 if (ptep_clear_flush_young_notify(vma, address,
878 pvmw.pte))
879 referenced++;
880 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
881 if (pmdp_clear_flush_young_notify(vma, address,
882 pvmw.pmd))
883 referenced++;
884 } else {
885 /* unexpected pmd-mapped folio? */
886 WARN_ON_ONCE(1);
887 }
888
889 pra->mapcount--;
890 }
891
892 if ((vma->vm_flags & VM_LOCKED) &&
893 folio_test_large(folio) &&
894 folio_within_vma(folio, vma)) {
895 unsigned long s_align, e_align;
896
897 s_align = ALIGN_DOWN(start, PMD_SIZE);
898 e_align = ALIGN_DOWN(start + folio_size(folio) - 1, PMD_SIZE);
899
900 /* folio doesn't cross page table boundary and fully mapped */
901 if ((s_align == e_align) && (ptes == folio_nr_pages(folio))) {
902 /* Restore the mlock which got missed */
903 mlock_vma_folio(folio, vma);
904 pra->vm_flags |= VM_LOCKED;
905 return false; /* To break the loop */
906 }
907 }
908
909 if (referenced)
910 folio_clear_idle(folio);
911 if (folio_test_clear_young(folio))
912 referenced++;
913
914 if (referenced) {
915 pra->referenced++;
916 pra->vm_flags |= vma->vm_flags & ~VM_LOCKED;
917 }
918
919 if (!pra->mapcount)
920 return false; /* To break the loop */
921
922 return true;
923}
924
925static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
926{
927 struct folio_referenced_arg *pra = arg;
928 struct mem_cgroup *memcg = pra->memcg;
929
930 /*
931 * Ignore references from this mapping if it has no recency. If the
932 * folio has been used in another mapping, we will catch it; if this
933 * other mapping is already gone, the unmap path will have set the
934 * referenced flag or activated the folio in zap_pte_range().
935 */
936 if (!vma_has_recency(vma))
937 return true;
938
939 /*
940 * If we are reclaiming on behalf of a cgroup, skip counting on behalf
941 * of references from different cgroups.
942 */
943 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
944 return true;
945
946 return false;
947}
948
949/**
950 * folio_referenced() - Test if the folio was referenced.
951 * @folio: The folio to test.
952 * @is_locked: Caller holds lock on the folio.
953 * @memcg: target memory cgroup
954 * @vm_flags: A combination of all the vma->vm_flags which referenced the folio.
955 *
956 * Quick test_and_clear_referenced for all mappings of a folio,
957 *
958 * Return: The number of mappings which referenced the folio. Return -1 if
959 * the function bailed out due to rmap lock contention.
960 */
961int folio_referenced(struct folio *folio, int is_locked,
962 struct mem_cgroup *memcg, unsigned long *vm_flags)
963{
964 int we_locked = 0;
965 struct folio_referenced_arg pra = {
966 .mapcount = folio_mapcount(folio),
967 .memcg = memcg,
968 };
969 struct rmap_walk_control rwc = {
970 .rmap_one = folio_referenced_one,
971 .arg = (void *)&pra,
972 .anon_lock = folio_lock_anon_vma_read,
973 .try_lock = true,
974 .invalid_vma = invalid_folio_referenced_vma,
975 };
976
977 *vm_flags = 0;
978 if (!pra.mapcount)
979 return 0;
980
981 if (!folio_raw_mapping(folio))
982 return 0;
983
984 if (!is_locked && (!folio_test_anon(folio) || folio_test_ksm(folio))) {
985 we_locked = folio_trylock(folio);
986 if (!we_locked)
987 return 1;
988 }
989
990 rmap_walk(folio, &rwc);
991 *vm_flags = pra.vm_flags;
992
993 if (we_locked)
994 folio_unlock(folio);
995
996 return rwc.contended ? -1 : pra.referenced;
997}
998
999static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw)
1000{
1001 int cleaned = 0;
1002 struct vm_area_struct *vma = pvmw->vma;
1003 struct mmu_notifier_range range;
1004 unsigned long address = pvmw->address;
1005
1006 /*
1007 * We have to assume the worse case ie pmd for invalidation. Note that
1008 * the folio can not be freed from this function.
1009 */
1010 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 0,
1011 vma->vm_mm, address, vma_address_end(pvmw));
1012 mmu_notifier_invalidate_range_start(&range);
1013
1014 while (page_vma_mapped_walk(pvmw)) {
1015 int ret = 0;
1016
1017 address = pvmw->address;
1018 if (pvmw->pte) {
1019 pte_t *pte = pvmw->pte;
1020 pte_t entry = ptep_get(pte);
1021
1022 if (!pte_dirty(entry) && !pte_write(entry))
1023 continue;
1024
1025 flush_cache_page(vma, address, pte_pfn(entry));
1026 entry = ptep_clear_flush(vma, address, pte);
1027 entry = pte_wrprotect(entry);
1028 entry = pte_mkclean(entry);
1029 set_pte_at(vma->vm_mm, address, pte, entry);
1030 ret = 1;
1031 } else {
1032#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1033 pmd_t *pmd = pvmw->pmd;
1034 pmd_t entry;
1035
1036 if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
1037 continue;
1038
1039 flush_cache_range(vma, address,
1040 address + HPAGE_PMD_SIZE);
1041 entry = pmdp_invalidate(vma, address, pmd);
1042 entry = pmd_wrprotect(entry);
1043 entry = pmd_mkclean(entry);
1044 set_pmd_at(vma->vm_mm, address, pmd, entry);
1045 ret = 1;
1046#else
1047 /* unexpected pmd-mapped folio? */
1048 WARN_ON_ONCE(1);
1049#endif
1050 }
1051
1052 if (ret)
1053 cleaned++;
1054 }
1055
1056 mmu_notifier_invalidate_range_end(&range);
1057
1058 return cleaned;
1059}
1060
1061static bool page_mkclean_one(struct folio *folio, struct vm_area_struct *vma,
1062 unsigned long address, void *arg)
1063{
1064 DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, PVMW_SYNC);
1065 int *cleaned = arg;
1066
1067 *cleaned += page_vma_mkclean_one(&pvmw);
1068
1069 return true;
1070}
1071
1072static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
1073{
1074 if (vma->vm_flags & VM_SHARED)
1075 return false;
1076
1077 return true;
1078}
1079
1080int folio_mkclean(struct folio *folio)
1081{
1082 int cleaned = 0;
1083 struct address_space *mapping;
1084 struct rmap_walk_control rwc = {
1085 .arg = (void *)&cleaned,
1086 .rmap_one = page_mkclean_one,
1087 .invalid_vma = invalid_mkclean_vma,
1088 };
1089
1090 BUG_ON(!folio_test_locked(folio));
1091
1092 if (!folio_mapped(folio))
1093 return 0;
1094
1095 mapping = folio_mapping(folio);
1096 if (!mapping)
1097 return 0;
1098
1099 rmap_walk(folio, &rwc);
1100
1101 return cleaned;
1102}
1103EXPORT_SYMBOL_GPL(folio_mkclean);
1104
1105/**
1106 * pfn_mkclean_range - Cleans the PTEs (including PMDs) mapped with range of
1107 * [@pfn, @pfn + @nr_pages) at the specific offset (@pgoff)
1108 * within the @vma of shared mappings. And since clean PTEs
1109 * should also be readonly, write protects them too.
1110 * @pfn: start pfn.
1111 * @nr_pages: number of physically contiguous pages srarting with @pfn.
1112 * @pgoff: page offset that the @pfn mapped with.
1113 * @vma: vma that @pfn mapped within.
1114 *
1115 * Returns the number of cleaned PTEs (including PMDs).
1116 */
1117int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff,
1118 struct vm_area_struct *vma)
1119{
1120 struct page_vma_mapped_walk pvmw = {
1121 .pfn = pfn,
1122 .nr_pages = nr_pages,
1123 .pgoff = pgoff,
1124 .vma = vma,
1125 .flags = PVMW_SYNC,
1126 };
1127
1128 if (invalid_mkclean_vma(vma, NULL))
1129 return 0;
1130
1131 pvmw.address = vma_pgoff_address(pgoff, nr_pages, vma);
1132 VM_BUG_ON_VMA(pvmw.address == -EFAULT, vma);
1133
1134 return page_vma_mkclean_one(&pvmw);
1135}
1136
1137int folio_total_mapcount(struct folio *folio)
1138{
1139 int mapcount = folio_entire_mapcount(folio);
1140 int nr_pages;
1141 int i;
1142
1143 /* In the common case, avoid the loop when no pages mapped by PTE */
1144 if (folio_nr_pages_mapped(folio) == 0)
1145 return mapcount;
1146 /*
1147 * Add all the PTE mappings of those pages mapped by PTE.
1148 * Limit the loop to folio_nr_pages_mapped()?
1149 * Perhaps: given all the raciness, that may be a good or a bad idea.
1150 */
1151 nr_pages = folio_nr_pages(folio);
1152 for (i = 0; i < nr_pages; i++)
1153 mapcount += atomic_read(&folio_page(folio, i)->_mapcount);
1154
1155 /* But each of those _mapcounts was based on -1 */
1156 mapcount += nr_pages;
1157 return mapcount;
1158}
1159
1160static __always_inline unsigned int __folio_add_rmap(struct folio *folio,
1161 struct page *page, int nr_pages, enum rmap_level level,
1162 int *nr_pmdmapped)
1163{
1164 atomic_t *mapped = &folio->_nr_pages_mapped;
1165 int first, nr = 0;
1166
1167 __folio_rmap_sanity_checks(folio, page, nr_pages, level);
1168
1169 switch (level) {
1170 case RMAP_LEVEL_PTE:
1171 do {
1172 first = atomic_inc_and_test(&page->_mapcount);
1173 if (first && folio_test_large(folio)) {
1174 first = atomic_inc_return_relaxed(mapped);
1175 first = (first < ENTIRELY_MAPPED);
1176 }
1177
1178 if (first)
1179 nr++;
1180 } while (page++, --nr_pages > 0);
1181 break;
1182 case RMAP_LEVEL_PMD:
1183 first = atomic_inc_and_test(&folio->_entire_mapcount);
1184 if (first) {
1185 nr = atomic_add_return_relaxed(ENTIRELY_MAPPED, mapped);
1186 if (likely(nr < ENTIRELY_MAPPED + ENTIRELY_MAPPED)) {
1187 *nr_pmdmapped = folio_nr_pages(folio);
1188 nr = *nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
1189 /* Raced ahead of a remove and another add? */
1190 if (unlikely(nr < 0))
1191 nr = 0;
1192 } else {
1193 /* Raced ahead of a remove of ENTIRELY_MAPPED */
1194 nr = 0;
1195 }
1196 }
1197 break;
1198 }
1199 return nr;
1200}
1201
1202/**
1203 * folio_move_anon_rmap - move a folio to our anon_vma
1204 * @folio: The folio to move to our anon_vma
1205 * @vma: The vma the folio belongs to
1206 *
1207 * When a folio belongs exclusively to one process after a COW event,
1208 * that folio can be moved into the anon_vma that belongs to just that
1209 * process, so the rmap code will not search the parent or sibling processes.
1210 */
1211void folio_move_anon_rmap(struct folio *folio, struct vm_area_struct *vma)
1212{
1213 void *anon_vma = vma->anon_vma;
1214
1215 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
1216 VM_BUG_ON_VMA(!anon_vma, vma);
1217
1218 anon_vma += PAGE_MAPPING_ANON;
1219 /*
1220 * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
1221 * simultaneously, so a concurrent reader (eg folio_referenced()'s
1222 * folio_test_anon()) will not see one without the other.
1223 */
1224 WRITE_ONCE(folio->mapping, anon_vma);
1225}
1226
1227/**
1228 * __folio_set_anon - set up a new anonymous rmap for a folio
1229 * @folio: The folio to set up the new anonymous rmap for.
1230 * @vma: VM area to add the folio to.
1231 * @address: User virtual address of the mapping
1232 * @exclusive: Whether the folio is exclusive to the process.
1233 */
1234static void __folio_set_anon(struct folio *folio, struct vm_area_struct *vma,
1235 unsigned long address, bool exclusive)
1236{
1237 struct anon_vma *anon_vma = vma->anon_vma;
1238
1239 BUG_ON(!anon_vma);
1240
1241 /*
1242 * If the folio isn't exclusive to this vma, we must use the _oldest_
1243 * possible anon_vma for the folio mapping!
1244 */
1245 if (!exclusive)
1246 anon_vma = anon_vma->root;
1247
1248 /*
1249 * page_idle does a lockless/optimistic rmap scan on folio->mapping.
1250 * Make sure the compiler doesn't split the stores of anon_vma and
1251 * the PAGE_MAPPING_ANON type identifier, otherwise the rmap code
1252 * could mistake the mapping for a struct address_space and crash.
1253 */
1254 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1255 WRITE_ONCE(folio->mapping, (struct address_space *) anon_vma);
1256 folio->index = linear_page_index(vma, address);
1257}
1258
1259/**
1260 * __page_check_anon_rmap - sanity check anonymous rmap addition
1261 * @folio: The folio containing @page.
1262 * @page: the page to check the mapping of
1263 * @vma: the vm area in which the mapping is added
1264 * @address: the user virtual address mapped
1265 */
1266static void __page_check_anon_rmap(struct folio *folio, struct page *page,
1267 struct vm_area_struct *vma, unsigned long address)
1268{
1269 /*
1270 * The page's anon-rmap details (mapping and index) are guaranteed to
1271 * be set up correctly at this point.
1272 *
1273 * We have exclusion against folio_add_anon_rmap_*() because the caller
1274 * always holds the page locked.
1275 *
1276 * We have exclusion against folio_add_new_anon_rmap because those pages
1277 * are initially only visible via the pagetables, and the pte is locked
1278 * over the call to folio_add_new_anon_rmap.
1279 */
1280 VM_BUG_ON_FOLIO(folio_anon_vma(folio)->root != vma->anon_vma->root,
1281 folio);
1282 VM_BUG_ON_PAGE(page_to_pgoff(page) != linear_page_index(vma, address),
1283 page);
1284}
1285
1286static __always_inline void __folio_add_anon_rmap(struct folio *folio,
1287 struct page *page, int nr_pages, struct vm_area_struct *vma,
1288 unsigned long address, rmap_t flags, enum rmap_level level)
1289{
1290 int i, nr, nr_pmdmapped = 0;
1291
1292 nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
1293 if (nr_pmdmapped)
1294 __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
1295 if (nr)
1296 __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
1297
1298 if (unlikely(!folio_test_anon(folio))) {
1299 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
1300 /*
1301 * For a PTE-mapped large folio, we only know that the single
1302 * PTE is exclusive. Further, __folio_set_anon() might not get
1303 * folio->index right when not given the address of the head
1304 * page.
1305 */
1306 VM_WARN_ON_FOLIO(folio_test_large(folio) &&
1307 level != RMAP_LEVEL_PMD, folio);
1308 __folio_set_anon(folio, vma, address,
1309 !!(flags & RMAP_EXCLUSIVE));
1310 } else if (likely(!folio_test_ksm(folio))) {
1311 __page_check_anon_rmap(folio, page, vma, address);
1312 }
1313
1314 if (flags & RMAP_EXCLUSIVE) {
1315 switch (level) {
1316 case RMAP_LEVEL_PTE:
1317 for (i = 0; i < nr_pages; i++)
1318 SetPageAnonExclusive(page + i);
1319 break;
1320 case RMAP_LEVEL_PMD:
1321 SetPageAnonExclusive(page);
1322 break;
1323 }
1324 }
1325 for (i = 0; i < nr_pages; i++) {
1326 struct page *cur_page = page + i;
1327
1328 /* While PTE-mapping a THP we have a PMD and a PTE mapping. */
1329 VM_WARN_ON_FOLIO((atomic_read(&cur_page->_mapcount) > 0 ||
1330 (folio_test_large(folio) &&
1331 folio_entire_mapcount(folio) > 1)) &&
1332 PageAnonExclusive(cur_page), folio);
1333 }
1334
1335 /*
1336 * For large folio, only mlock it if it's fully mapped to VMA. It's
1337 * not easy to check whether the large folio is fully mapped to VMA
1338 * here. Only mlock normal 4K folio and leave page reclaim to handle
1339 * large folio.
1340 */
1341 if (!folio_test_large(folio))
1342 mlock_vma_folio(folio, vma);
1343}
1344
1345/**
1346 * folio_add_anon_rmap_ptes - add PTE mappings to a page range of an anon folio
1347 * @folio: The folio to add the mappings to
1348 * @page: The first page to add
1349 * @nr_pages: The number of pages which will be mapped
1350 * @vma: The vm area in which the mappings are added
1351 * @address: The user virtual address of the first page to map
1352 * @flags: The rmap flags
1353 *
1354 * The page range of folio is defined by [first_page, first_page + nr_pages)
1355 *
1356 * The caller needs to hold the page table lock, and the page must be locked in
1357 * the anon_vma case: to serialize mapping,index checking after setting,
1358 * and to ensure that an anon folio is not being upgraded racily to a KSM folio
1359 * (but KSM folios are never downgraded).
1360 */
1361void folio_add_anon_rmap_ptes(struct folio *folio, struct page *page,
1362 int nr_pages, struct vm_area_struct *vma, unsigned long address,
1363 rmap_t flags)
1364{
1365 __folio_add_anon_rmap(folio, page, nr_pages, vma, address, flags,
1366 RMAP_LEVEL_PTE);
1367}
1368
1369/**
1370 * folio_add_anon_rmap_pmd - add a PMD mapping to a page range of an anon folio
1371 * @folio: The folio to add the mapping to
1372 * @page: The first page to add
1373 * @vma: The vm area in which the mapping is added
1374 * @address: The user virtual address of the first page to map
1375 * @flags: The rmap flags
1376 *
1377 * The page range of folio is defined by [first_page, first_page + HPAGE_PMD_NR)
1378 *
1379 * The caller needs to hold the page table lock, and the page must be locked in
1380 * the anon_vma case: to serialize mapping,index checking after setting.
1381 */
1382void folio_add_anon_rmap_pmd(struct folio *folio, struct page *page,
1383 struct vm_area_struct *vma, unsigned long address, rmap_t flags)
1384{
1385#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1386 __folio_add_anon_rmap(folio, page, HPAGE_PMD_NR, vma, address, flags,
1387 RMAP_LEVEL_PMD);
1388#else
1389 WARN_ON_ONCE(true);
1390#endif
1391}
1392
1393/**
1394 * folio_add_new_anon_rmap - Add mapping to a new anonymous folio.
1395 * @folio: The folio to add the mapping to.
1396 * @vma: the vm area in which the mapping is added
1397 * @address: the user virtual address mapped
1398 *
1399 * Like folio_add_anon_rmap_*() but must only be called on *new* folios.
1400 * This means the inc-and-test can be bypassed.
1401 * The folio does not have to be locked.
1402 *
1403 * If the folio is pmd-mappable, it is accounted as a THP. As the folio
1404 * is new, it's assumed to be mapped exclusively by a single process.
1405 */
1406void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
1407 unsigned long address)
1408{
1409 int nr = folio_nr_pages(folio);
1410
1411 VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
1412 VM_BUG_ON_VMA(address < vma->vm_start ||
1413 address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
1414 __folio_set_swapbacked(folio);
1415 __folio_set_anon(folio, vma, address, true);
1416
1417 if (likely(!folio_test_large(folio))) {
1418 /* increment count (starts at -1) */
1419 atomic_set(&folio->_mapcount, 0);
1420 SetPageAnonExclusive(&folio->page);
1421 } else if (!folio_test_pmd_mappable(folio)) {
1422 int i;
1423
1424 for (i = 0; i < nr; i++) {
1425 struct page *page = folio_page(folio, i);
1426
1427 /* increment count (starts at -1) */
1428 atomic_set(&page->_mapcount, 0);
1429 SetPageAnonExclusive(page);
1430 }
1431
1432 atomic_set(&folio->_nr_pages_mapped, nr);
1433 } else {
1434 /* increment count (starts at -1) */
1435 atomic_set(&folio->_entire_mapcount, 0);
1436 atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED);
1437 SetPageAnonExclusive(&folio->page);
1438 __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr);
1439 }
1440
1441 __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
1442}
1443
1444static __always_inline void __folio_add_file_rmap(struct folio *folio,
1445 struct page *page, int nr_pages, struct vm_area_struct *vma,
1446 enum rmap_level level)
1447{
1448 int nr, nr_pmdmapped = 0;
1449
1450 VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
1451
1452 nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
1453 if (nr_pmdmapped)
1454 __lruvec_stat_mod_folio(folio, folio_test_swapbacked(folio) ?
1455 NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped);
1456 if (nr)
1457 __lruvec_stat_mod_folio(folio, NR_FILE_MAPPED, nr);
1458
1459 /* See comments in folio_add_anon_rmap_*() */
1460 if (!folio_test_large(folio))
1461 mlock_vma_folio(folio, vma);
1462}
1463
1464/**
1465 * folio_add_file_rmap_ptes - add PTE mappings to a page range of a folio
1466 * @folio: The folio to add the mappings to
1467 * @page: The first page to add
1468 * @nr_pages: The number of pages that will be mapped using PTEs
1469 * @vma: The vm area in which the mappings are added
1470 *
1471 * The page range of the folio is defined by [page, page + nr_pages)
1472 *
1473 * The caller needs to hold the page table lock.
1474 */
1475void folio_add_file_rmap_ptes(struct folio *folio, struct page *page,
1476 int nr_pages, struct vm_area_struct *vma)
1477{
1478 __folio_add_file_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);
1479}
1480
1481/**
1482 * folio_add_file_rmap_pmd - add a PMD mapping to a page range of a folio
1483 * @folio: The folio to add the mapping to
1484 * @page: The first page to add
1485 * @vma: The vm area in which the mapping is added
1486 *
1487 * The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
1488 *
1489 * The caller needs to hold the page table lock.
1490 */
1491void folio_add_file_rmap_pmd(struct folio *folio, struct page *page,
1492 struct vm_area_struct *vma)
1493{
1494#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1495 __folio_add_file_rmap(folio, page, HPAGE_PMD_NR, vma, RMAP_LEVEL_PMD);
1496#else
1497 WARN_ON_ONCE(true);
1498#endif
1499}
1500
1501static __always_inline void __folio_remove_rmap(struct folio *folio,
1502 struct page *page, int nr_pages, struct vm_area_struct *vma,
1503 enum rmap_level level)
1504{
1505 atomic_t *mapped = &folio->_nr_pages_mapped;
1506 int last, nr = 0, nr_pmdmapped = 0;
1507 enum node_stat_item idx;
1508
1509 __folio_rmap_sanity_checks(folio, page, nr_pages, level);
1510
1511 switch (level) {
1512 case RMAP_LEVEL_PTE:
1513 do {
1514 last = atomic_add_negative(-1, &page->_mapcount);
1515 if (last && folio_test_large(folio)) {
1516 last = atomic_dec_return_relaxed(mapped);
1517 last = (last < ENTIRELY_MAPPED);
1518 }
1519
1520 if (last)
1521 nr++;
1522 } while (page++, --nr_pages > 0);
1523 break;
1524 case RMAP_LEVEL_PMD:
1525 last = atomic_add_negative(-1, &folio->_entire_mapcount);
1526 if (last) {
1527 nr = atomic_sub_return_relaxed(ENTIRELY_MAPPED, mapped);
1528 if (likely(nr < ENTIRELY_MAPPED)) {
1529 nr_pmdmapped = folio_nr_pages(folio);
1530 nr = nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
1531 /* Raced ahead of another remove and an add? */
1532 if (unlikely(nr < 0))
1533 nr = 0;
1534 } else {
1535 /* An add of ENTIRELY_MAPPED raced ahead */
1536 nr = 0;
1537 }
1538 }
1539 break;
1540 }
1541
1542 if (nr_pmdmapped) {
1543 if (folio_test_anon(folio))
1544 idx = NR_ANON_THPS;
1545 else if (folio_test_swapbacked(folio))
1546 idx = NR_SHMEM_PMDMAPPED;
1547 else
1548 idx = NR_FILE_PMDMAPPED;
1549 __lruvec_stat_mod_folio(folio, idx, -nr_pmdmapped);
1550 }
1551 if (nr) {
1552 idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED;
1553 __lruvec_stat_mod_folio(folio, idx, -nr);
1554
1555 /*
1556 * Queue anon large folio for deferred split if at least one
1557 * page of the folio is unmapped and at least one page
1558 * is still mapped.
1559 */
1560 if (folio_test_large(folio) && folio_test_anon(folio))
1561 if (level == RMAP_LEVEL_PTE || nr < nr_pmdmapped)
1562 deferred_split_folio(folio);
1563 }
1564
1565 /*
1566 * It would be tidy to reset folio_test_anon mapping when fully
1567 * unmapped, but that might overwrite a racing folio_add_anon_rmap_*()
1568 * which increments mapcount after us but sets mapping before us:
1569 * so leave the reset to free_pages_prepare, and remember that
1570 * it's only reliable while mapped.
1571 */
1572
1573 munlock_vma_folio(folio, vma);
1574}
1575
1576/**
1577 * folio_remove_rmap_ptes - remove PTE mappings from a page range of a folio
1578 * @folio: The folio to remove the mappings from
1579 * @page: The first page to remove
1580 * @nr_pages: The number of pages that will be removed from the mapping
1581 * @vma: The vm area from which the mappings are removed
1582 *
1583 * The page range of the folio is defined by [page, page + nr_pages)
1584 *
1585 * The caller needs to hold the page table lock.
1586 */
1587void folio_remove_rmap_ptes(struct folio *folio, struct page *page,
1588 int nr_pages, struct vm_area_struct *vma)
1589{
1590 __folio_remove_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);
1591}
1592
1593/**
1594 * folio_remove_rmap_pmd - remove a PMD mapping from a page range of a folio
1595 * @folio: The folio to remove the mapping from
1596 * @page: The first page to remove
1597 * @vma: The vm area from which the mapping is removed
1598 *
1599 * The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
1600 *
1601 * The caller needs to hold the page table lock.
1602 */
1603void folio_remove_rmap_pmd(struct folio *folio, struct page *page,
1604 struct vm_area_struct *vma)
1605{
1606#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1607 __folio_remove_rmap(folio, page, HPAGE_PMD_NR, vma, RMAP_LEVEL_PMD);
1608#else
1609 WARN_ON_ONCE(true);
1610#endif
1611}
1612
1613/*
1614 * @arg: enum ttu_flags will be passed to this argument
1615 */
1616static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
1617 unsigned long address, void *arg)
1618{
1619 struct mm_struct *mm = vma->vm_mm;
1620 DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
1621 pte_t pteval;
1622 struct page *subpage;
1623 bool anon_exclusive, ret = true;
1624 struct mmu_notifier_range range;
1625 enum ttu_flags flags = (enum ttu_flags)(long)arg;
1626 unsigned long pfn;
1627 unsigned long hsz = 0;
1628
1629 /*
1630 * When racing against e.g. zap_pte_range() on another cpu,
1631 * in between its ptep_get_and_clear_full() and folio_remove_rmap_*(),
1632 * try_to_unmap() may return before page_mapped() has become false,
1633 * if page table locking is skipped: use TTU_SYNC to wait for that.
1634 */
1635 if (flags & TTU_SYNC)
1636 pvmw.flags = PVMW_SYNC;
1637
1638 if (flags & TTU_SPLIT_HUGE_PMD)
1639 split_huge_pmd_address(vma, address, false, folio);
1640
1641 /*
1642 * For THP, we have to assume the worse case ie pmd for invalidation.
1643 * For hugetlb, it could be much worse if we need to do pud
1644 * invalidation in the case of pmd sharing.
1645 *
1646 * Note that the folio can not be freed in this function as call of
1647 * try_to_unmap() must hold a reference on the folio.
1648 */
1649 range.end = vma_address_end(&pvmw);
1650 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
1651 address, range.end);
1652 if (folio_test_hugetlb(folio)) {
1653 /*
1654 * If sharing is possible, start and end will be adjusted
1655 * accordingly.
1656 */
1657 adjust_range_if_pmd_sharing_possible(vma, &range.start,
1658 &range.end);
1659
1660 /* We need the huge page size for set_huge_pte_at() */
1661 hsz = huge_page_size(hstate_vma(vma));
1662 }
1663 mmu_notifier_invalidate_range_start(&range);
1664
1665 while (page_vma_mapped_walk(&pvmw)) {
1666 /* Unexpected PMD-mapped THP? */
1667 VM_BUG_ON_FOLIO(!pvmw.pte, folio);
1668
1669 /*
1670 * If the folio is in an mlock()d vma, we must not swap it out.
1671 */
1672 if (!(flags & TTU_IGNORE_MLOCK) &&
1673 (vma->vm_flags & VM_LOCKED)) {
1674 /* Restore the mlock which got missed */
1675 if (!folio_test_large(folio))
1676 mlock_vma_folio(folio, vma);
1677 page_vma_mapped_walk_done(&pvmw);
1678 ret = false;
1679 break;
1680 }
1681
1682 pfn = pte_pfn(ptep_get(pvmw.pte));
1683 subpage = folio_page(folio, pfn - folio_pfn(folio));
1684 address = pvmw.address;
1685 anon_exclusive = folio_test_anon(folio) &&
1686 PageAnonExclusive(subpage);
1687
1688 if (folio_test_hugetlb(folio)) {
1689 bool anon = folio_test_anon(folio);
1690
1691 /*
1692 * The try_to_unmap() is only passed a hugetlb page
1693 * in the case where the hugetlb page is poisoned.
1694 */
1695 VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage);
1696 /*
1697 * huge_pmd_unshare may unmap an entire PMD page.
1698 * There is no way of knowing exactly which PMDs may
1699 * be cached for this mm, so we must flush them all.
1700 * start/end were already adjusted above to cover this
1701 * range.
1702 */
1703 flush_cache_range(vma, range.start, range.end);
1704
1705 /*
1706 * To call huge_pmd_unshare, i_mmap_rwsem must be
1707 * held in write mode. Caller needs to explicitly
1708 * do this outside rmap routines.
1709 *
1710 * We also must hold hugetlb vma_lock in write mode.
1711 * Lock order dictates acquiring vma_lock BEFORE
1712 * i_mmap_rwsem. We can only try lock here and fail
1713 * if unsuccessful.
1714 */
1715 if (!anon) {
1716 VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
1717 if (!hugetlb_vma_trylock_write(vma)) {
1718 page_vma_mapped_walk_done(&pvmw);
1719 ret = false;
1720 break;
1721 }
1722 if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
1723 hugetlb_vma_unlock_write(vma);
1724 flush_tlb_range(vma,
1725 range.start, range.end);
1726 /*
1727 * The ref count of the PMD page was
1728 * dropped which is part of the way map
1729 * counting is done for shared PMDs.
1730 * Return 'true' here. When there is
1731 * no other sharing, huge_pmd_unshare
1732 * returns false and we will unmap the
1733 * actual page and drop map count
1734 * to zero.
1735 */
1736 page_vma_mapped_walk_done(&pvmw);
1737 break;
1738 }
1739 hugetlb_vma_unlock_write(vma);
1740 }
1741 pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
1742 } else {
1743 flush_cache_page(vma, address, pfn);
1744 /* Nuke the page table entry. */
1745 if (should_defer_flush(mm, flags)) {
1746 /*
1747 * We clear the PTE but do not flush so potentially
1748 * a remote CPU could still be writing to the folio.
1749 * If the entry was previously clean then the
1750 * architecture must guarantee that a clear->dirty
1751 * transition on a cached TLB entry is written through
1752 * and traps if the PTE is unmapped.
1753 */
1754 pteval = ptep_get_and_clear(mm, address, pvmw.pte);
1755
1756 set_tlb_ubc_flush_pending(mm, pteval, address);
1757 } else {
1758 pteval = ptep_clear_flush(vma, address, pvmw.pte);
1759 }
1760 }
1761
1762 /*
1763 * Now the pte is cleared. If this pte was uffd-wp armed,
1764 * we may want to replace a none pte with a marker pte if
1765 * it's file-backed, so we don't lose the tracking info.
1766 */
1767 pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
1768
1769 /* Set the dirty flag on the folio now the pte is gone. */
1770 if (pte_dirty(pteval))
1771 folio_mark_dirty(folio);
1772
1773 /* Update high watermark before we lower rss */
1774 update_hiwater_rss(mm);
1775
1776 if (PageHWPoison(subpage) && (flags & TTU_HWPOISON)) {
1777 pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
1778 if (folio_test_hugetlb(folio)) {
1779 hugetlb_count_sub(folio_nr_pages(folio), mm);
1780 set_huge_pte_at(mm, address, pvmw.pte, pteval,
1781 hsz);
1782 } else {
1783 dec_mm_counter(mm, mm_counter(&folio->page));
1784 set_pte_at(mm, address, pvmw.pte, pteval);
1785 }
1786
1787 } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
1788 /*
1789 * The guest indicated that the page content is of no
1790 * interest anymore. Simply discard the pte, vmscan
1791 * will take care of the rest.
1792 * A future reference will then fault in a new zero
1793 * page. When userfaultfd is active, we must not drop
1794 * this page though, as its main user (postcopy
1795 * migration) will not expect userfaults on already
1796 * copied pages.
1797 */
1798 dec_mm_counter(mm, mm_counter(&folio->page));
1799 } else if (folio_test_anon(folio)) {
1800 swp_entry_t entry = page_swap_entry(subpage);
1801 pte_t swp_pte;
1802 /*
1803 * Store the swap location in the pte.
1804 * See handle_pte_fault() ...
1805 */
1806 if (unlikely(folio_test_swapbacked(folio) !=
1807 folio_test_swapcache(folio))) {
1808 WARN_ON_ONCE(1);
1809 ret = false;
1810 page_vma_mapped_walk_done(&pvmw);
1811 break;
1812 }
1813
1814 /* MADV_FREE page check */
1815 if (!folio_test_swapbacked(folio)) {
1816 int ref_count, map_count;
1817
1818 /*
1819 * Synchronize with gup_pte_range():
1820 * - clear PTE; barrier; read refcount
1821 * - inc refcount; barrier; read PTE
1822 */
1823 smp_mb();
1824
1825 ref_count = folio_ref_count(folio);
1826 map_count = folio_mapcount(folio);
1827
1828 /*
1829 * Order reads for page refcount and dirty flag
1830 * (see comments in __remove_mapping()).
1831 */
1832 smp_rmb();
1833
1834 /*
1835 * The only page refs must be one from isolation
1836 * plus the rmap(s) (dropped by discard:).
1837 */
1838 if (ref_count == 1 + map_count &&
1839 !folio_test_dirty(folio)) {
1840 dec_mm_counter(mm, MM_ANONPAGES);
1841 goto discard;
1842 }
1843
1844 /*
1845 * If the folio was redirtied, it cannot be
1846 * discarded. Remap the page to page table.
1847 */
1848 set_pte_at(mm, address, pvmw.pte, pteval);
1849 folio_set_swapbacked(folio);
1850 ret = false;
1851 page_vma_mapped_walk_done(&pvmw);
1852 break;
1853 }
1854
1855 if (swap_duplicate(entry) < 0) {
1856 set_pte_at(mm, address, pvmw.pte, pteval);
1857 ret = false;
1858 page_vma_mapped_walk_done(&pvmw);
1859 break;
1860 }
1861 if (arch_unmap_one(mm, vma, address, pteval) < 0) {
1862 swap_free(entry);
1863 set_pte_at(mm, address, pvmw.pte, pteval);
1864 ret = false;
1865 page_vma_mapped_walk_done(&pvmw);
1866 break;
1867 }
1868
1869 /* See folio_try_share_anon_rmap(): clear PTE first. */
1870 if (anon_exclusive &&
1871 folio_try_share_anon_rmap_pte(folio, subpage)) {
1872 swap_free(entry);
1873 set_pte_at(mm, address, pvmw.pte, pteval);
1874 ret = false;
1875 page_vma_mapped_walk_done(&pvmw);
1876 break;
1877 }
1878 if (list_empty(&mm->mmlist)) {
1879 spin_lock(&mmlist_lock);
1880 if (list_empty(&mm->mmlist))
1881 list_add(&mm->mmlist, &init_mm.mmlist);
1882 spin_unlock(&mmlist_lock);
1883 }
1884 dec_mm_counter(mm, MM_ANONPAGES);
1885 inc_mm_counter(mm, MM_SWAPENTS);
1886 swp_pte = swp_entry_to_pte(entry);
1887 if (anon_exclusive)
1888 swp_pte = pte_swp_mkexclusive(swp_pte);
1889 if (pte_soft_dirty(pteval))
1890 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1891 if (pte_uffd_wp(pteval))
1892 swp_pte = pte_swp_mkuffd_wp(swp_pte);
1893 set_pte_at(mm, address, pvmw.pte, swp_pte);
1894 } else {
1895 /*
1896 * This is a locked file-backed folio,
1897 * so it cannot be removed from the page
1898 * cache and replaced by a new folio before
1899 * mmu_notifier_invalidate_range_end, so no
1900 * concurrent thread might update its page table
1901 * to point at a new folio while a device is
1902 * still using this folio.
1903 *
1904 * See Documentation/mm/mmu_notifier.rst
1905 */
1906 dec_mm_counter(mm, mm_counter_file(&folio->page));
1907 }
1908discard:
1909 if (unlikely(folio_test_hugetlb(folio)))
1910 hugetlb_remove_rmap(folio);
1911 else
1912 folio_remove_rmap_pte(folio, subpage, vma);
1913 if (vma->vm_flags & VM_LOCKED)
1914 mlock_drain_local();
1915 folio_put(folio);
1916 }
1917
1918 mmu_notifier_invalidate_range_end(&range);
1919
1920 return ret;
1921}
1922
1923static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
1924{
1925 return vma_is_temporary_stack(vma);
1926}
1927
1928static int folio_not_mapped(struct folio *folio)
1929{
1930 return !folio_mapped(folio);
1931}
1932
1933/**
1934 * try_to_unmap - Try to remove all page table mappings to a folio.
1935 * @folio: The folio to unmap.
1936 * @flags: action and flags
1937 *
1938 * Tries to remove all the page table entries which are mapping this
1939 * folio. It is the caller's responsibility to check if the folio is
1940 * still mapped if needed (use TTU_SYNC to prevent accounting races).
1941 *
1942 * Context: Caller must hold the folio lock.
1943 */
1944void try_to_unmap(struct folio *folio, enum ttu_flags flags)
1945{
1946 struct rmap_walk_control rwc = {
1947 .rmap_one = try_to_unmap_one,
1948 .arg = (void *)flags,
1949 .done = folio_not_mapped,
1950 .anon_lock = folio_lock_anon_vma_read,
1951 };
1952
1953 if (flags & TTU_RMAP_LOCKED)
1954 rmap_walk_locked(folio, &rwc);
1955 else
1956 rmap_walk(folio, &rwc);
1957}
1958
1959/*
1960 * @arg: enum ttu_flags will be passed to this argument.
1961 *
1962 * If TTU_SPLIT_HUGE_PMD is specified any PMD mappings will be split into PTEs
1963 * containing migration entries.
1964 */
1965static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
1966 unsigned long address, void *arg)
1967{
1968 struct mm_struct *mm = vma->vm_mm;
1969 DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
1970 pte_t pteval;
1971 struct page *subpage;
1972 bool anon_exclusive, ret = true;
1973 struct mmu_notifier_range range;
1974 enum ttu_flags flags = (enum ttu_flags)(long)arg;
1975 unsigned long pfn;
1976 unsigned long hsz = 0;
1977
1978 /*
1979 * When racing against e.g. zap_pte_range() on another cpu,
1980 * in between its ptep_get_and_clear_full() and folio_remove_rmap_*(),
1981 * try_to_migrate() may return before page_mapped() has become false,
1982 * if page table locking is skipped: use TTU_SYNC to wait for that.
1983 */
1984 if (flags & TTU_SYNC)
1985 pvmw.flags = PVMW_SYNC;
1986
1987 /*
1988 * unmap_page() in mm/huge_memory.c is the only user of migration with
1989 * TTU_SPLIT_HUGE_PMD and it wants to freeze.
1990 */
1991 if (flags & TTU_SPLIT_HUGE_PMD)
1992 split_huge_pmd_address(vma, address, true, folio);
1993
1994 /*
1995 * For THP, we have to assume the worse case ie pmd for invalidation.
1996 * For hugetlb, it could be much worse if we need to do pud
1997 * invalidation in the case of pmd sharing.
1998 *
1999 * Note that the page can not be free in this function as call of
2000 * try_to_unmap() must hold a reference on the page.
2001 */
2002 range.end = vma_address_end(&pvmw);
2003 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
2004 address, range.end);
2005 if (folio_test_hugetlb(folio)) {
2006 /*
2007 * If sharing is possible, start and end will be adjusted
2008 * accordingly.
2009 */
2010 adjust_range_if_pmd_sharing_possible(vma, &range.start,
2011 &range.end);
2012
2013 /* We need the huge page size for set_huge_pte_at() */
2014 hsz = huge_page_size(hstate_vma(vma));
2015 }
2016 mmu_notifier_invalidate_range_start(&range);
2017
2018 while (page_vma_mapped_walk(&pvmw)) {
2019#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2020 /* PMD-mapped THP migration entry */
2021 if (!pvmw.pte) {
2022 subpage = folio_page(folio,
2023 pmd_pfn(*pvmw.pmd) - folio_pfn(folio));
2024 VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
2025 !folio_test_pmd_mappable(folio), folio);
2026
2027 if (set_pmd_migration_entry(&pvmw, subpage)) {
2028 ret = false;
2029 page_vma_mapped_walk_done(&pvmw);
2030 break;
2031 }
2032 continue;
2033 }
2034#endif
2035
2036 /* Unexpected PMD-mapped THP? */
2037 VM_BUG_ON_FOLIO(!pvmw.pte, folio);
2038
2039 pfn = pte_pfn(ptep_get(pvmw.pte));
2040
2041 if (folio_is_zone_device(folio)) {
2042 /*
2043 * Our PTE is a non-present device exclusive entry and
2044 * calculating the subpage as for the common case would
2045 * result in an invalid pointer.
2046 *
2047 * Since only PAGE_SIZE pages can currently be
2048 * migrated, just set it to page. This will need to be
2049 * changed when hugepage migrations to device private
2050 * memory are supported.
2051 */
2052 VM_BUG_ON_FOLIO(folio_nr_pages(folio) > 1, folio);
2053 subpage = &folio->page;
2054 } else {
2055 subpage = folio_page(folio, pfn - folio_pfn(folio));
2056 }
2057 address = pvmw.address;
2058 anon_exclusive = folio_test_anon(folio) &&
2059 PageAnonExclusive(subpage);
2060
2061 if (folio_test_hugetlb(folio)) {
2062 bool anon = folio_test_anon(folio);
2063
2064 /*
2065 * huge_pmd_unshare may unmap an entire PMD page.
2066 * There is no way of knowing exactly which PMDs may
2067 * be cached for this mm, so we must flush them all.
2068 * start/end were already adjusted above to cover this
2069 * range.
2070 */
2071 flush_cache_range(vma, range.start, range.end);
2072
2073 /*
2074 * To call huge_pmd_unshare, i_mmap_rwsem must be
2075 * held in write mode. Caller needs to explicitly
2076 * do this outside rmap routines.
2077 *
2078 * We also must hold hugetlb vma_lock in write mode.
2079 * Lock order dictates acquiring vma_lock BEFORE
2080 * i_mmap_rwsem. We can only try lock here and
2081 * fail if unsuccessful.
2082 */
2083 if (!anon) {
2084 VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
2085 if (!hugetlb_vma_trylock_write(vma)) {
2086 page_vma_mapped_walk_done(&pvmw);
2087 ret = false;
2088 break;
2089 }
2090 if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
2091 hugetlb_vma_unlock_write(vma);
2092 flush_tlb_range(vma,
2093 range.start, range.end);
2094
2095 /*
2096 * The ref count of the PMD page was
2097 * dropped which is part of the way map
2098 * counting is done for shared PMDs.
2099 * Return 'true' here. When there is
2100 * no other sharing, huge_pmd_unshare
2101 * returns false and we will unmap the
2102 * actual page and drop map count
2103 * to zero.
2104 */
2105 page_vma_mapped_walk_done(&pvmw);
2106 break;
2107 }
2108 hugetlb_vma_unlock_write(vma);
2109 }
2110 /* Nuke the hugetlb page table entry */
2111 pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
2112 } else {
2113 flush_cache_page(vma, address, pfn);
2114 /* Nuke the page table entry. */
2115 if (should_defer_flush(mm, flags)) {
2116 /*
2117 * We clear the PTE but do not flush so potentially
2118 * a remote CPU could still be writing to the folio.
2119 * If the entry was previously clean then the
2120 * architecture must guarantee that a clear->dirty
2121 * transition on a cached TLB entry is written through
2122 * and traps if the PTE is unmapped.
2123 */
2124 pteval = ptep_get_and_clear(mm, address, pvmw.pte);
2125
2126 set_tlb_ubc_flush_pending(mm, pteval, address);
2127 } else {
2128 pteval = ptep_clear_flush(vma, address, pvmw.pte);
2129 }
2130 }
2131
2132 /* Set the dirty flag on the folio now the pte is gone. */
2133 if (pte_dirty(pteval))
2134 folio_mark_dirty(folio);
2135
2136 /* Update high watermark before we lower rss */
2137 update_hiwater_rss(mm);
2138
2139 if (folio_is_device_private(folio)) {
2140 unsigned long pfn = folio_pfn(folio);
2141 swp_entry_t entry;
2142 pte_t swp_pte;
2143
2144 if (anon_exclusive)
2145 WARN_ON_ONCE(folio_try_share_anon_rmap_pte(folio,
2146 subpage));
2147
2148 /*
2149 * Store the pfn of the page in a special migration
2150 * pte. do_swap_page() will wait until the migration
2151 * pte is removed and then restart fault handling.
2152 */
2153 entry = pte_to_swp_entry(pteval);
2154 if (is_writable_device_private_entry(entry))
2155 entry = make_writable_migration_entry(pfn);
2156 else if (anon_exclusive)
2157 entry = make_readable_exclusive_migration_entry(pfn);
2158 else
2159 entry = make_readable_migration_entry(pfn);
2160 swp_pte = swp_entry_to_pte(entry);
2161
2162 /*
2163 * pteval maps a zone device page and is therefore
2164 * a swap pte.
2165 */
2166 if (pte_swp_soft_dirty(pteval))
2167 swp_pte = pte_swp_mksoft_dirty(swp_pte);
2168 if (pte_swp_uffd_wp(pteval))
2169 swp_pte = pte_swp_mkuffd_wp(swp_pte);
2170 set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte);
2171 trace_set_migration_pte(pvmw.address, pte_val(swp_pte),
2172 compound_order(&folio->page));
2173 /*
2174 * No need to invalidate here it will synchronize on
2175 * against the special swap migration pte.
2176 */
2177 } else if (PageHWPoison(subpage)) {
2178 pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
2179 if (folio_test_hugetlb(folio)) {
2180 hugetlb_count_sub(folio_nr_pages(folio), mm);
2181 set_huge_pte_at(mm, address, pvmw.pte, pteval,
2182 hsz);
2183 } else {
2184 dec_mm_counter(mm, mm_counter(&folio->page));
2185 set_pte_at(mm, address, pvmw.pte, pteval);
2186 }
2187
2188 } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) {
2189 /*
2190 * The guest indicated that the page content is of no
2191 * interest anymore. Simply discard the pte, vmscan
2192 * will take care of the rest.
2193 * A future reference will then fault in a new zero
2194 * page. When userfaultfd is active, we must not drop
2195 * this page though, as its main user (postcopy
2196 * migration) will not expect userfaults on already
2197 * copied pages.
2198 */
2199 dec_mm_counter(mm, mm_counter(&folio->page));
2200 } else {
2201 swp_entry_t entry;
2202 pte_t swp_pte;
2203
2204 if (arch_unmap_one(mm, vma, address, pteval) < 0) {
2205 if (folio_test_hugetlb(folio))
2206 set_huge_pte_at(mm, address, pvmw.pte,
2207 pteval, hsz);
2208 else
2209 set_pte_at(mm, address, pvmw.pte, pteval);
2210 ret = false;
2211 page_vma_mapped_walk_done(&pvmw);
2212 break;
2213 }
2214 VM_BUG_ON_PAGE(pte_write(pteval) && folio_test_anon(folio) &&
2215 !anon_exclusive, subpage);
2216
2217 /* See folio_try_share_anon_rmap_pte(): clear PTE first. */
2218 if (folio_test_hugetlb(folio)) {
2219 if (anon_exclusive &&
2220 hugetlb_try_share_anon_rmap(folio)) {
2221 set_huge_pte_at(mm, address, pvmw.pte,
2222 pteval, hsz);
2223 ret = false;
2224 page_vma_mapped_walk_done(&pvmw);
2225 break;
2226 }
2227 } else if (anon_exclusive &&
2228 folio_try_share_anon_rmap_pte(folio, subpage)) {
2229 set_pte_at(mm, address, pvmw.pte, pteval);
2230 ret = false;
2231 page_vma_mapped_walk_done(&pvmw);
2232 break;
2233 }
2234
2235 /*
2236 * Store the pfn of the page in a special migration
2237 * pte. do_swap_page() will wait until the migration
2238 * pte is removed and then restart fault handling.
2239 */
2240 if (pte_write(pteval))
2241 entry = make_writable_migration_entry(
2242 page_to_pfn(subpage));
2243 else if (anon_exclusive)
2244 entry = make_readable_exclusive_migration_entry(
2245 page_to_pfn(subpage));
2246 else
2247 entry = make_readable_migration_entry(
2248 page_to_pfn(subpage));
2249 if (pte_young(pteval))
2250 entry = make_migration_entry_young(entry);
2251 if (pte_dirty(pteval))
2252 entry = make_migration_entry_dirty(entry);
2253 swp_pte = swp_entry_to_pte(entry);
2254 if (pte_soft_dirty(pteval))
2255 swp_pte = pte_swp_mksoft_dirty(swp_pte);
2256 if (pte_uffd_wp(pteval))
2257 swp_pte = pte_swp_mkuffd_wp(swp_pte);
2258 if (folio_test_hugetlb(folio))
2259 set_huge_pte_at(mm, address, pvmw.pte, swp_pte,
2260 hsz);
2261 else
2262 set_pte_at(mm, address, pvmw.pte, swp_pte);
2263 trace_set_migration_pte(address, pte_val(swp_pte),
2264 compound_order(&folio->page));
2265 /*
2266 * No need to invalidate here it will synchronize on
2267 * against the special swap migration pte.
2268 */
2269 }
2270
2271 if (unlikely(folio_test_hugetlb(folio)))
2272 hugetlb_remove_rmap(folio);
2273 else
2274 folio_remove_rmap_pte(folio, subpage, vma);
2275 if (vma->vm_flags & VM_LOCKED)
2276 mlock_drain_local();
2277 folio_put(folio);
2278 }
2279
2280 mmu_notifier_invalidate_range_end(&range);
2281
2282 return ret;
2283}
2284
2285/**
2286 * try_to_migrate - try to replace all page table mappings with swap entries
2287 * @folio: the folio to replace page table entries for
2288 * @flags: action and flags
2289 *
2290 * Tries to remove all the page table entries which are mapping this folio and
2291 * replace them with special swap entries. Caller must hold the folio lock.
2292 */
2293void try_to_migrate(struct folio *folio, enum ttu_flags flags)
2294{
2295 struct rmap_walk_control rwc = {
2296 .rmap_one = try_to_migrate_one,
2297 .arg = (void *)flags,
2298 .done = folio_not_mapped,
2299 .anon_lock = folio_lock_anon_vma_read,
2300 };
2301
2302 /*
2303 * Migration always ignores mlock and only supports TTU_RMAP_LOCKED and
2304 * TTU_SPLIT_HUGE_PMD, TTU_SYNC, and TTU_BATCH_FLUSH flags.
2305 */
2306 if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
2307 TTU_SYNC | TTU_BATCH_FLUSH)))
2308 return;
2309
2310 if (folio_is_zone_device(folio) &&
2311 (!folio_is_device_private(folio) && !folio_is_device_coherent(folio)))
2312 return;
2313
2314 /*
2315 * During exec, a temporary VMA is setup and later moved.
2316 * The VMA is moved under the anon_vma lock but not the
2317 * page tables leading to a race where migration cannot
2318 * find the migration ptes. Rather than increasing the
2319 * locking requirements of exec(), migration skips
2320 * temporary VMAs until after exec() completes.
2321 */
2322 if (!folio_test_ksm(folio) && folio_test_anon(folio))
2323 rwc.invalid_vma = invalid_migration_vma;
2324
2325 if (flags & TTU_RMAP_LOCKED)
2326 rmap_walk_locked(folio, &rwc);
2327 else
2328 rmap_walk(folio, &rwc);
2329}
2330
2331#ifdef CONFIG_DEVICE_PRIVATE
2332struct make_exclusive_args {
2333 struct mm_struct *mm;
2334 unsigned long address;
2335 void *owner;
2336 bool valid;
2337};
2338
2339static bool page_make_device_exclusive_one(struct folio *folio,
2340 struct vm_area_struct *vma, unsigned long address, void *priv)
2341{
2342 struct mm_struct *mm = vma->vm_mm;
2343 DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
2344 struct make_exclusive_args *args = priv;
2345 pte_t pteval;
2346 struct page *subpage;
2347 bool ret = true;
2348 struct mmu_notifier_range range;
2349 swp_entry_t entry;
2350 pte_t swp_pte;
2351 pte_t ptent;
2352
2353 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0,
2354 vma->vm_mm, address, min(vma->vm_end,
2355 address + folio_size(folio)),
2356 args->owner);
2357 mmu_notifier_invalidate_range_start(&range);
2358
2359 while (page_vma_mapped_walk(&pvmw)) {
2360 /* Unexpected PMD-mapped THP? */
2361 VM_BUG_ON_FOLIO(!pvmw.pte, folio);
2362
2363 ptent = ptep_get(pvmw.pte);
2364 if (!pte_present(ptent)) {
2365 ret = false;
2366 page_vma_mapped_walk_done(&pvmw);
2367 break;
2368 }
2369
2370 subpage = folio_page(folio,
2371 pte_pfn(ptent) - folio_pfn(folio));
2372 address = pvmw.address;
2373
2374 /* Nuke the page table entry. */
2375 flush_cache_page(vma, address, pte_pfn(ptent));
2376 pteval = ptep_clear_flush(vma, address, pvmw.pte);
2377
2378 /* Set the dirty flag on the folio now the pte is gone. */
2379 if (pte_dirty(pteval))
2380 folio_mark_dirty(folio);
2381
2382 /*
2383 * Check that our target page is still mapped at the expected
2384 * address.
2385 */
2386 if (args->mm == mm && args->address == address &&
2387 pte_write(pteval))
2388 args->valid = true;
2389
2390 /*
2391 * Store the pfn of the page in a special migration
2392 * pte. do_swap_page() will wait until the migration
2393 * pte is removed and then restart fault handling.
2394 */
2395 if (pte_write(pteval))
2396 entry = make_writable_device_exclusive_entry(
2397 page_to_pfn(subpage));
2398 else
2399 entry = make_readable_device_exclusive_entry(
2400 page_to_pfn(subpage));
2401 swp_pte = swp_entry_to_pte(entry);
2402 if (pte_soft_dirty(pteval))
2403 swp_pte = pte_swp_mksoft_dirty(swp_pte);
2404 if (pte_uffd_wp(pteval))
2405 swp_pte = pte_swp_mkuffd_wp(swp_pte);
2406
2407 set_pte_at(mm, address, pvmw.pte, swp_pte);
2408
2409 /*
2410 * There is a reference on the page for the swap entry which has
2411 * been removed, so shouldn't take another.
2412 */
2413 folio_remove_rmap_pte(folio, subpage, vma);
2414 }
2415
2416 mmu_notifier_invalidate_range_end(&range);
2417
2418 return ret;
2419}
2420
2421/**
2422 * folio_make_device_exclusive - Mark the folio exclusively owned by a device.
2423 * @folio: The folio to replace page table entries for.
2424 * @mm: The mm_struct where the folio is expected to be mapped.
2425 * @address: Address where the folio is expected to be mapped.
2426 * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier callbacks
2427 *
2428 * Tries to remove all the page table entries which are mapping this
2429 * folio and replace them with special device exclusive swap entries to
2430 * grant a device exclusive access to the folio.
2431 *
2432 * Context: Caller must hold the folio lock.
2433 * Return: false if the page is still mapped, or if it could not be unmapped
2434 * from the expected address. Otherwise returns true (success).
2435 */
2436static bool folio_make_device_exclusive(struct folio *folio,
2437 struct mm_struct *mm, unsigned long address, void *owner)
2438{
2439 struct make_exclusive_args args = {
2440 .mm = mm,
2441 .address = address,
2442 .owner = owner,
2443 .valid = false,
2444 };
2445 struct rmap_walk_control rwc = {
2446 .rmap_one = page_make_device_exclusive_one,
2447 .done = folio_not_mapped,
2448 .anon_lock = folio_lock_anon_vma_read,
2449 .arg = &args,
2450 };
2451
2452 /*
2453 * Restrict to anonymous folios for now to avoid potential writeback
2454 * issues.
2455 */
2456 if (!folio_test_anon(folio))
2457 return false;
2458
2459 rmap_walk(folio, &rwc);
2460
2461 return args.valid && !folio_mapcount(folio);
2462}
2463
2464/**
2465 * make_device_exclusive_range() - Mark a range for exclusive use by a device
2466 * @mm: mm_struct of associated target process
2467 * @start: start of the region to mark for exclusive device access
2468 * @end: end address of region
2469 * @pages: returns the pages which were successfully marked for exclusive access
2470 * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier to allow filtering
2471 *
2472 * Returns: number of pages found in the range by GUP. A page is marked for
2473 * exclusive access only if the page pointer is non-NULL.
2474 *
2475 * This function finds ptes mapping page(s) to the given address range, locks
2476 * them and replaces mappings with special swap entries preventing userspace CPU
2477 * access. On fault these entries are replaced with the original mapping after
2478 * calling MMU notifiers.
2479 *
2480 * A driver using this to program access from a device must use a mmu notifier
2481 * critical section to hold a device specific lock during programming. Once
2482 * programming is complete it should drop the page lock and reference after
2483 * which point CPU access to the page will revoke the exclusive access.
2484 */
2485int make_device_exclusive_range(struct mm_struct *mm, unsigned long start,
2486 unsigned long end, struct page **pages,
2487 void *owner)
2488{
2489 long npages = (end - start) >> PAGE_SHIFT;
2490 long i;
2491
2492 npages = get_user_pages_remote(mm, start, npages,
2493 FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD,
2494 pages, NULL);
2495 if (npages < 0)
2496 return npages;
2497
2498 for (i = 0; i < npages; i++, start += PAGE_SIZE) {
2499 struct folio *folio = page_folio(pages[i]);
2500 if (PageTail(pages[i]) || !folio_trylock(folio)) {
2501 folio_put(folio);
2502 pages[i] = NULL;
2503 continue;
2504 }
2505
2506 if (!folio_make_device_exclusive(folio, mm, start, owner)) {
2507 folio_unlock(folio);
2508 folio_put(folio);
2509 pages[i] = NULL;
2510 }
2511 }
2512
2513 return npages;
2514}
2515EXPORT_SYMBOL_GPL(make_device_exclusive_range);
2516#endif
2517
2518void __put_anon_vma(struct anon_vma *anon_vma)
2519{
2520 struct anon_vma *root = anon_vma->root;
2521
2522 anon_vma_free(anon_vma);
2523 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
2524 anon_vma_free(root);
2525}
2526
2527static struct anon_vma *rmap_walk_anon_lock(struct folio *folio,
2528 struct rmap_walk_control *rwc)
2529{
2530 struct anon_vma *anon_vma;
2531
2532 if (rwc->anon_lock)
2533 return rwc->anon_lock(folio, rwc);
2534
2535 /*
2536 * Note: remove_migration_ptes() cannot use folio_lock_anon_vma_read()
2537 * because that depends on page_mapped(); but not all its usages
2538 * are holding mmap_lock. Users without mmap_lock are required to
2539 * take a reference count to prevent the anon_vma disappearing
2540 */
2541 anon_vma = folio_anon_vma(folio);
2542 if (!anon_vma)
2543 return NULL;
2544
2545 if (anon_vma_trylock_read(anon_vma))
2546 goto out;
2547
2548 if (rwc->try_lock) {
2549 anon_vma = NULL;
2550 rwc->contended = true;
2551 goto out;
2552 }
2553
2554 anon_vma_lock_read(anon_vma);
2555out:
2556 return anon_vma;
2557}
2558
2559/*
2560 * rmap_walk_anon - do something to anonymous page using the object-based
2561 * rmap method
2562 * @folio: the folio to be handled
2563 * @rwc: control variable according to each walk type
2564 * @locked: caller holds relevant rmap lock
2565 *
2566 * Find all the mappings of a folio using the mapping pointer and the vma
2567 * chains contained in the anon_vma struct it points to.
2568 */
2569static void rmap_walk_anon(struct folio *folio,
2570 struct rmap_walk_control *rwc, bool locked)
2571{
2572 struct anon_vma *anon_vma;
2573 pgoff_t pgoff_start, pgoff_end;
2574 struct anon_vma_chain *avc;
2575
2576 if (locked) {
2577 anon_vma = folio_anon_vma(folio);
2578 /* anon_vma disappear under us? */
2579 VM_BUG_ON_FOLIO(!anon_vma, folio);
2580 } else {
2581 anon_vma = rmap_walk_anon_lock(folio, rwc);
2582 }
2583 if (!anon_vma)
2584 return;
2585
2586 pgoff_start = folio_pgoff(folio);
2587 pgoff_end = pgoff_start + folio_nr_pages(folio) - 1;
2588 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root,
2589 pgoff_start, pgoff_end) {
2590 struct vm_area_struct *vma = avc->vma;
2591 unsigned long address = vma_address(&folio->page, vma);
2592
2593 VM_BUG_ON_VMA(address == -EFAULT, vma);
2594 cond_resched();
2595
2596 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
2597 continue;
2598
2599 if (!rwc->rmap_one(folio, vma, address, rwc->arg))
2600 break;
2601 if (rwc->done && rwc->done(folio))
2602 break;
2603 }
2604
2605 if (!locked)
2606 anon_vma_unlock_read(anon_vma);
2607}
2608
2609/*
2610 * rmap_walk_file - do something to file page using the object-based rmap method
2611 * @folio: the folio to be handled
2612 * @rwc: control variable according to each walk type
2613 * @locked: caller holds relevant rmap lock
2614 *
2615 * Find all the mappings of a folio using the mapping pointer and the vma chains
2616 * contained in the address_space struct it points to.
2617 */
2618static void rmap_walk_file(struct folio *folio,
2619 struct rmap_walk_control *rwc, bool locked)
2620{
2621 struct address_space *mapping = folio_mapping(folio);
2622 pgoff_t pgoff_start, pgoff_end;
2623 struct vm_area_struct *vma;
2624
2625 /*
2626 * The page lock not only makes sure that page->mapping cannot
2627 * suddenly be NULLified by truncation, it makes sure that the
2628 * structure at mapping cannot be freed and reused yet,
2629 * so we can safely take mapping->i_mmap_rwsem.
2630 */
2631 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
2632
2633 if (!mapping)
2634 return;
2635
2636 pgoff_start = folio_pgoff(folio);
2637 pgoff_end = pgoff_start + folio_nr_pages(folio) - 1;
2638 if (!locked) {
2639 if (i_mmap_trylock_read(mapping))
2640 goto lookup;
2641
2642 if (rwc->try_lock) {
2643 rwc->contended = true;
2644 return;
2645 }
2646
2647 i_mmap_lock_read(mapping);
2648 }
2649lookup:
2650 vma_interval_tree_foreach(vma, &mapping->i_mmap,
2651 pgoff_start, pgoff_end) {
2652 unsigned long address = vma_address(&folio->page, vma);
2653
2654 VM_BUG_ON_VMA(address == -EFAULT, vma);
2655 cond_resched();
2656
2657 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
2658 continue;
2659
2660 if (!rwc->rmap_one(folio, vma, address, rwc->arg))
2661 goto done;
2662 if (rwc->done && rwc->done(folio))
2663 goto done;
2664 }
2665
2666done:
2667 if (!locked)
2668 i_mmap_unlock_read(mapping);
2669}
2670
2671void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc)
2672{
2673 if (unlikely(folio_test_ksm(folio)))
2674 rmap_walk_ksm(folio, rwc);
2675 else if (folio_test_anon(folio))
2676 rmap_walk_anon(folio, rwc, false);
2677 else
2678 rmap_walk_file(folio, rwc, false);
2679}
2680
2681/* Like rmap_walk, but caller holds relevant rmap lock */
2682void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc)
2683{
2684 /* no ksm support for now */
2685 VM_BUG_ON_FOLIO(folio_test_ksm(folio), folio);
2686 if (folio_test_anon(folio))
2687 rmap_walk_anon(folio, rwc, true);
2688 else
2689 rmap_walk_file(folio, rwc, true);
2690}
2691
2692#ifdef CONFIG_HUGETLB_PAGE
2693/*
2694 * The following two functions are for anonymous (private mapped) hugepages.
2695 * Unlike common anonymous pages, anonymous hugepages have no accounting code
2696 * and no lru code, because we handle hugepages differently from common pages.
2697 */
2698void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
2699 unsigned long address, rmap_t flags)
2700{
2701 VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
2702 VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
2703
2704 atomic_inc(&folio->_entire_mapcount);
2705 if (flags & RMAP_EXCLUSIVE)
2706 SetPageAnonExclusive(&folio->page);
2707 VM_WARN_ON_FOLIO(folio_entire_mapcount(folio) > 1 &&
2708 PageAnonExclusive(&folio->page), folio);
2709}
2710
2711void hugetlb_add_new_anon_rmap(struct folio *folio,
2712 struct vm_area_struct *vma, unsigned long address)
2713{
2714 VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
2715
2716 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
2717 /* increment count (starts at -1) */
2718 atomic_set(&folio->_entire_mapcount, 0);
2719 folio_clear_hugetlb_restore_reserve(folio);
2720 __folio_set_anon(folio, vma, address, true);
2721 SetPageAnonExclusive(&folio->page);
2722}
2723#endif /* CONFIG_HUGETLB_PAGE */
1/*
2 * mm/rmap.c - physical to virtual reverse mappings
3 *
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL).
6 *
7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible.
9 *
10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode.
13 *
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins 2003, 2004
18 */
19
20/*
21 * Lock ordering in mm:
22 *
23 * inode->i_mutex (while writing or truncating, not reading or faulting)
24 * mm->mmap_sem
25 * page->flags PG_locked (lock_page)
26 * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
27 * mapping->i_mmap_rwsem
28 * anon_vma->rwsem
29 * mm->page_table_lock or pte_lock
30 * zone_lru_lock (in mark_page_accessed, isolate_lru_page)
31 * swap_lock (in swap_duplicate, swap_info_get)
32 * mmlist_lock (in mmput, drain_mmlist and others)
33 * mapping->private_lock (in __set_page_dirty_buffers)
34 * mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
35 * mapping->tree_lock (widely used)
36 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
37 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
38 * sb_lock (within inode_lock in fs/fs-writeback.c)
39 * mapping->tree_lock (widely used, in set_page_dirty,
40 * in arch-dependent flush_dcache_mmap_lock,
41 * within bdi.wb->list_lock in __sync_single_inode)
42 *
43 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
44 * ->tasklist_lock
45 * pte map lock
46 */
47
48#include <linux/mm.h>
49#include <linux/pagemap.h>
50#include <linux/swap.h>
51#include <linux/swapops.h>
52#include <linux/slab.h>
53#include <linux/init.h>
54#include <linux/ksm.h>
55#include <linux/rmap.h>
56#include <linux/rcupdate.h>
57#include <linux/export.h>
58#include <linux/memcontrol.h>
59#include <linux/mmu_notifier.h>
60#include <linux/migrate.h>
61#include <linux/hugetlb.h>
62#include <linux/backing-dev.h>
63#include <linux/page_idle.h>
64
65#include <asm/tlbflush.h>
66
67#include <trace/events/tlb.h>
68
69#include "internal.h"
70
71static struct kmem_cache *anon_vma_cachep;
72static struct kmem_cache *anon_vma_chain_cachep;
73
74static inline struct anon_vma *anon_vma_alloc(void)
75{
76 struct anon_vma *anon_vma;
77
78 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
79 if (anon_vma) {
80 atomic_set(&anon_vma->refcount, 1);
81 anon_vma->degree = 1; /* Reference for first vma */
82 anon_vma->parent = anon_vma;
83 /*
84 * Initialise the anon_vma root to point to itself. If called
85 * from fork, the root will be reset to the parents anon_vma.
86 */
87 anon_vma->root = anon_vma;
88 }
89
90 return anon_vma;
91}
92
93static inline void anon_vma_free(struct anon_vma *anon_vma)
94{
95 VM_BUG_ON(atomic_read(&anon_vma->refcount));
96
97 /*
98 * Synchronize against page_lock_anon_vma_read() such that
99 * we can safely hold the lock without the anon_vma getting
100 * freed.
101 *
102 * Relies on the full mb implied by the atomic_dec_and_test() from
103 * put_anon_vma() against the acquire barrier implied by
104 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
105 *
106 * page_lock_anon_vma_read() VS put_anon_vma()
107 * down_read_trylock() atomic_dec_and_test()
108 * LOCK MB
109 * atomic_read() rwsem_is_locked()
110 *
111 * LOCK should suffice since the actual taking of the lock must
112 * happen _before_ what follows.
113 */
114 might_sleep();
115 if (rwsem_is_locked(&anon_vma->root->rwsem)) {
116 anon_vma_lock_write(anon_vma);
117 anon_vma_unlock_write(anon_vma);
118 }
119
120 kmem_cache_free(anon_vma_cachep, anon_vma);
121}
122
123static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
124{
125 return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
126}
127
128static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
129{
130 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
131}
132
133static void anon_vma_chain_link(struct vm_area_struct *vma,
134 struct anon_vma_chain *avc,
135 struct anon_vma *anon_vma)
136{
137 avc->vma = vma;
138 avc->anon_vma = anon_vma;
139 list_add(&avc->same_vma, &vma->anon_vma_chain);
140 anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
141}
142
143/**
144 * __anon_vma_prepare - attach an anon_vma to a memory region
145 * @vma: the memory region in question
146 *
147 * This makes sure the memory mapping described by 'vma' has
148 * an 'anon_vma' attached to it, so that we can associate the
149 * anonymous pages mapped into it with that anon_vma.
150 *
151 * The common case will be that we already have one, which
152 * is handled inline by anon_vma_prepare(). But if
153 * not we either need to find an adjacent mapping that we
154 * can re-use the anon_vma from (very common when the only
155 * reason for splitting a vma has been mprotect()), or we
156 * allocate a new one.
157 *
158 * Anon-vma allocations are very subtle, because we may have
159 * optimistically looked up an anon_vma in page_lock_anon_vma_read()
160 * and that may actually touch the spinlock even in the newly
161 * allocated vma (it depends on RCU to make sure that the
162 * anon_vma isn't actually destroyed).
163 *
164 * As a result, we need to do proper anon_vma locking even
165 * for the new allocation. At the same time, we do not want
166 * to do any locking for the common case of already having
167 * an anon_vma.
168 *
169 * This must be called with the mmap_sem held for reading.
170 */
171int __anon_vma_prepare(struct vm_area_struct *vma)
172{
173 struct mm_struct *mm = vma->vm_mm;
174 struct anon_vma *anon_vma, *allocated;
175 struct anon_vma_chain *avc;
176
177 might_sleep();
178
179 avc = anon_vma_chain_alloc(GFP_KERNEL);
180 if (!avc)
181 goto out_enomem;
182
183 anon_vma = find_mergeable_anon_vma(vma);
184 allocated = NULL;
185 if (!anon_vma) {
186 anon_vma = anon_vma_alloc();
187 if (unlikely(!anon_vma))
188 goto out_enomem_free_avc;
189 allocated = anon_vma;
190 }
191
192 anon_vma_lock_write(anon_vma);
193 /* page_table_lock to protect against threads */
194 spin_lock(&mm->page_table_lock);
195 if (likely(!vma->anon_vma)) {
196 vma->anon_vma = anon_vma;
197 anon_vma_chain_link(vma, avc, anon_vma);
198 /* vma reference or self-parent link for new root */
199 anon_vma->degree++;
200 allocated = NULL;
201 avc = NULL;
202 }
203 spin_unlock(&mm->page_table_lock);
204 anon_vma_unlock_write(anon_vma);
205
206 if (unlikely(allocated))
207 put_anon_vma(allocated);
208 if (unlikely(avc))
209 anon_vma_chain_free(avc);
210
211 return 0;
212
213 out_enomem_free_avc:
214 anon_vma_chain_free(avc);
215 out_enomem:
216 return -ENOMEM;
217}
218
219/*
220 * This is a useful helper function for locking the anon_vma root as
221 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
222 * have the same vma.
223 *
224 * Such anon_vma's should have the same root, so you'd expect to see
225 * just a single mutex_lock for the whole traversal.
226 */
227static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
228{
229 struct anon_vma *new_root = anon_vma->root;
230 if (new_root != root) {
231 if (WARN_ON_ONCE(root))
232 up_write(&root->rwsem);
233 root = new_root;
234 down_write(&root->rwsem);
235 }
236 return root;
237}
238
239static inline void unlock_anon_vma_root(struct anon_vma *root)
240{
241 if (root)
242 up_write(&root->rwsem);
243}
244
245/*
246 * Attach the anon_vmas from src to dst.
247 * Returns 0 on success, -ENOMEM on failure.
248 *
249 * If dst->anon_vma is NULL this function tries to find and reuse existing
250 * anon_vma which has no vmas and only one child anon_vma. This prevents
251 * degradation of anon_vma hierarchy to endless linear chain in case of
252 * constantly forking task. On the other hand, an anon_vma with more than one
253 * child isn't reused even if there was no alive vma, thus rmap walker has a
254 * good chance of avoiding scanning the whole hierarchy when it searches where
255 * page is mapped.
256 */
257int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
258{
259 struct anon_vma_chain *avc, *pavc;
260 struct anon_vma *root = NULL;
261
262 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
263 struct anon_vma *anon_vma;
264
265 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
266 if (unlikely(!avc)) {
267 unlock_anon_vma_root(root);
268 root = NULL;
269 avc = anon_vma_chain_alloc(GFP_KERNEL);
270 if (!avc)
271 goto enomem_failure;
272 }
273 anon_vma = pavc->anon_vma;
274 root = lock_anon_vma_root(root, anon_vma);
275 anon_vma_chain_link(dst, avc, anon_vma);
276
277 /*
278 * Reuse existing anon_vma if its degree lower than two,
279 * that means it has no vma and only one anon_vma child.
280 *
281 * Do not chose parent anon_vma, otherwise first child
282 * will always reuse it. Root anon_vma is never reused:
283 * it has self-parent reference and at least one child.
284 */
285 if (!dst->anon_vma && anon_vma != src->anon_vma &&
286 anon_vma->degree < 2)
287 dst->anon_vma = anon_vma;
288 }
289 if (dst->anon_vma)
290 dst->anon_vma->degree++;
291 unlock_anon_vma_root(root);
292 return 0;
293
294 enomem_failure:
295 /*
296 * dst->anon_vma is dropped here otherwise its degree can be incorrectly
297 * decremented in unlink_anon_vmas().
298 * We can safely do this because callers of anon_vma_clone() don't care
299 * about dst->anon_vma if anon_vma_clone() failed.
300 */
301 dst->anon_vma = NULL;
302 unlink_anon_vmas(dst);
303 return -ENOMEM;
304}
305
306/*
307 * Attach vma to its own anon_vma, as well as to the anon_vmas that
308 * the corresponding VMA in the parent process is attached to.
309 * Returns 0 on success, non-zero on failure.
310 */
311int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
312{
313 struct anon_vma_chain *avc;
314 struct anon_vma *anon_vma;
315 int error;
316
317 /* Don't bother if the parent process has no anon_vma here. */
318 if (!pvma->anon_vma)
319 return 0;
320
321 /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
322 vma->anon_vma = NULL;
323
324 /*
325 * First, attach the new VMA to the parent VMA's anon_vmas,
326 * so rmap can find non-COWed pages in child processes.
327 */
328 error = anon_vma_clone(vma, pvma);
329 if (error)
330 return error;
331
332 /* An existing anon_vma has been reused, all done then. */
333 if (vma->anon_vma)
334 return 0;
335
336 /* Then add our own anon_vma. */
337 anon_vma = anon_vma_alloc();
338 if (!anon_vma)
339 goto out_error;
340 avc = anon_vma_chain_alloc(GFP_KERNEL);
341 if (!avc)
342 goto out_error_free_anon_vma;
343
344 /*
345 * The root anon_vma's spinlock is the lock actually used when we
346 * lock any of the anon_vmas in this anon_vma tree.
347 */
348 anon_vma->root = pvma->anon_vma->root;
349 anon_vma->parent = pvma->anon_vma;
350 /*
351 * With refcounts, an anon_vma can stay around longer than the
352 * process it belongs to. The root anon_vma needs to be pinned until
353 * this anon_vma is freed, because the lock lives in the root.
354 */
355 get_anon_vma(anon_vma->root);
356 /* Mark this anon_vma as the one where our new (COWed) pages go. */
357 vma->anon_vma = anon_vma;
358 anon_vma_lock_write(anon_vma);
359 anon_vma_chain_link(vma, avc, anon_vma);
360 anon_vma->parent->degree++;
361 anon_vma_unlock_write(anon_vma);
362
363 return 0;
364
365 out_error_free_anon_vma:
366 put_anon_vma(anon_vma);
367 out_error:
368 unlink_anon_vmas(vma);
369 return -ENOMEM;
370}
371
372void unlink_anon_vmas(struct vm_area_struct *vma)
373{
374 struct anon_vma_chain *avc, *next;
375 struct anon_vma *root = NULL;
376
377 /*
378 * Unlink each anon_vma chained to the VMA. This list is ordered
379 * from newest to oldest, ensuring the root anon_vma gets freed last.
380 */
381 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
382 struct anon_vma *anon_vma = avc->anon_vma;
383
384 root = lock_anon_vma_root(root, anon_vma);
385 anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
386
387 /*
388 * Leave empty anon_vmas on the list - we'll need
389 * to free them outside the lock.
390 */
391 if (RB_EMPTY_ROOT(&anon_vma->rb_root)) {
392 anon_vma->parent->degree--;
393 continue;
394 }
395
396 list_del(&avc->same_vma);
397 anon_vma_chain_free(avc);
398 }
399 if (vma->anon_vma)
400 vma->anon_vma->degree--;
401 unlock_anon_vma_root(root);
402
403 /*
404 * Iterate the list once more, it now only contains empty and unlinked
405 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
406 * needing to write-acquire the anon_vma->root->rwsem.
407 */
408 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
409 struct anon_vma *anon_vma = avc->anon_vma;
410
411 VM_WARN_ON(anon_vma->degree);
412 put_anon_vma(anon_vma);
413
414 list_del(&avc->same_vma);
415 anon_vma_chain_free(avc);
416 }
417}
418
419static void anon_vma_ctor(void *data)
420{
421 struct anon_vma *anon_vma = data;
422
423 init_rwsem(&anon_vma->rwsem);
424 atomic_set(&anon_vma->refcount, 0);
425 anon_vma->rb_root = RB_ROOT;
426}
427
428void __init anon_vma_init(void)
429{
430 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
431 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
432 anon_vma_ctor);
433 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
434 SLAB_PANIC|SLAB_ACCOUNT);
435}
436
437/*
438 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
439 *
440 * Since there is no serialization what so ever against page_remove_rmap()
441 * the best this function can do is return a locked anon_vma that might
442 * have been relevant to this page.
443 *
444 * The page might have been remapped to a different anon_vma or the anon_vma
445 * returned may already be freed (and even reused).
446 *
447 * In case it was remapped to a different anon_vma, the new anon_vma will be a
448 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
449 * ensure that any anon_vma obtained from the page will still be valid for as
450 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
451 *
452 * All users of this function must be very careful when walking the anon_vma
453 * chain and verify that the page in question is indeed mapped in it
454 * [ something equivalent to page_mapped_in_vma() ].
455 *
456 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
457 * that the anon_vma pointer from page->mapping is valid if there is a
458 * mapcount, we can dereference the anon_vma after observing those.
459 */
460struct anon_vma *page_get_anon_vma(struct page *page)
461{
462 struct anon_vma *anon_vma = NULL;
463 unsigned long anon_mapping;
464
465 rcu_read_lock();
466 anon_mapping = (unsigned long)READ_ONCE(page->mapping);
467 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
468 goto out;
469 if (!page_mapped(page))
470 goto out;
471
472 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
473 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
474 anon_vma = NULL;
475 goto out;
476 }
477
478 /*
479 * If this page is still mapped, then its anon_vma cannot have been
480 * freed. But if it has been unmapped, we have no security against the
481 * anon_vma structure being freed and reused (for another anon_vma:
482 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
483 * above cannot corrupt).
484 */
485 if (!page_mapped(page)) {
486 rcu_read_unlock();
487 put_anon_vma(anon_vma);
488 return NULL;
489 }
490out:
491 rcu_read_unlock();
492
493 return anon_vma;
494}
495
496/*
497 * Similar to page_get_anon_vma() except it locks the anon_vma.
498 *
499 * Its a little more complex as it tries to keep the fast path to a single
500 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
501 * reference like with page_get_anon_vma() and then block on the mutex.
502 */
503struct anon_vma *page_lock_anon_vma_read(struct page *page)
504{
505 struct anon_vma *anon_vma = NULL;
506 struct anon_vma *root_anon_vma;
507 unsigned long anon_mapping;
508
509 rcu_read_lock();
510 anon_mapping = (unsigned long)READ_ONCE(page->mapping);
511 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
512 goto out;
513 if (!page_mapped(page))
514 goto out;
515
516 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
517 root_anon_vma = READ_ONCE(anon_vma->root);
518 if (down_read_trylock(&root_anon_vma->rwsem)) {
519 /*
520 * If the page is still mapped, then this anon_vma is still
521 * its anon_vma, and holding the mutex ensures that it will
522 * not go away, see anon_vma_free().
523 */
524 if (!page_mapped(page)) {
525 up_read(&root_anon_vma->rwsem);
526 anon_vma = NULL;
527 }
528 goto out;
529 }
530
531 /* trylock failed, we got to sleep */
532 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
533 anon_vma = NULL;
534 goto out;
535 }
536
537 if (!page_mapped(page)) {
538 rcu_read_unlock();
539 put_anon_vma(anon_vma);
540 return NULL;
541 }
542
543 /* we pinned the anon_vma, its safe to sleep */
544 rcu_read_unlock();
545 anon_vma_lock_read(anon_vma);
546
547 if (atomic_dec_and_test(&anon_vma->refcount)) {
548 /*
549 * Oops, we held the last refcount, release the lock
550 * and bail -- can't simply use put_anon_vma() because
551 * we'll deadlock on the anon_vma_lock_write() recursion.
552 */
553 anon_vma_unlock_read(anon_vma);
554 __put_anon_vma(anon_vma);
555 anon_vma = NULL;
556 }
557
558 return anon_vma;
559
560out:
561 rcu_read_unlock();
562 return anon_vma;
563}
564
565void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
566{
567 anon_vma_unlock_read(anon_vma);
568}
569
570#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
571/*
572 * Flush TLB entries for recently unmapped pages from remote CPUs. It is
573 * important if a PTE was dirty when it was unmapped that it's flushed
574 * before any IO is initiated on the page to prevent lost writes. Similarly,
575 * it must be flushed before freeing to prevent data leakage.
576 */
577void try_to_unmap_flush(void)
578{
579 struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
580 int cpu;
581
582 if (!tlb_ubc->flush_required)
583 return;
584
585 cpu = get_cpu();
586
587 if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask)) {
588 count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
589 local_flush_tlb();
590 trace_tlb_flush(TLB_LOCAL_SHOOTDOWN, TLB_FLUSH_ALL);
591 }
592
593 if (cpumask_any_but(&tlb_ubc->cpumask, cpu) < nr_cpu_ids)
594 flush_tlb_others(&tlb_ubc->cpumask, NULL, 0, TLB_FLUSH_ALL);
595 cpumask_clear(&tlb_ubc->cpumask);
596 tlb_ubc->flush_required = false;
597 tlb_ubc->writable = false;
598 put_cpu();
599}
600
601/* Flush iff there are potentially writable TLB entries that can race with IO */
602void try_to_unmap_flush_dirty(void)
603{
604 struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
605
606 if (tlb_ubc->writable)
607 try_to_unmap_flush();
608}
609
610static void set_tlb_ubc_flush_pending(struct mm_struct *mm,
611 struct page *page, bool writable)
612{
613 struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
614
615 cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm));
616 tlb_ubc->flush_required = true;
617
618 /*
619 * If the PTE was dirty then it's best to assume it's writable. The
620 * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
621 * before the page is queued for IO.
622 */
623 if (writable)
624 tlb_ubc->writable = true;
625}
626
627/*
628 * Returns true if the TLB flush should be deferred to the end of a batch of
629 * unmap operations to reduce IPIs.
630 */
631static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
632{
633 bool should_defer = false;
634
635 if (!(flags & TTU_BATCH_FLUSH))
636 return false;
637
638 /* If remote CPUs need to be flushed then defer batch the flush */
639 if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
640 should_defer = true;
641 put_cpu();
642
643 return should_defer;
644}
645#else
646static void set_tlb_ubc_flush_pending(struct mm_struct *mm,
647 struct page *page, bool writable)
648{
649}
650
651static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
652{
653 return false;
654}
655#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
656
657/*
658 * At what user virtual address is page expected in vma?
659 * Caller should check the page is actually part of the vma.
660 */
661unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
662{
663 unsigned long address;
664 if (PageAnon(page)) {
665 struct anon_vma *page__anon_vma = page_anon_vma(page);
666 /*
667 * Note: swapoff's unuse_vma() is more efficient with this
668 * check, and needs it to match anon_vma when KSM is active.
669 */
670 if (!vma->anon_vma || !page__anon_vma ||
671 vma->anon_vma->root != page__anon_vma->root)
672 return -EFAULT;
673 } else if (page->mapping) {
674 if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
675 return -EFAULT;
676 } else
677 return -EFAULT;
678 address = __vma_address(page, vma);
679 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
680 return -EFAULT;
681 return address;
682}
683
684pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
685{
686 pgd_t *pgd;
687 pud_t *pud;
688 pmd_t *pmd = NULL;
689 pmd_t pmde;
690
691 pgd = pgd_offset(mm, address);
692 if (!pgd_present(*pgd))
693 goto out;
694
695 pud = pud_offset(pgd, address);
696 if (!pud_present(*pud))
697 goto out;
698
699 pmd = pmd_offset(pud, address);
700 /*
701 * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
702 * without holding anon_vma lock for write. So when looking for a
703 * genuine pmde (in which to find pte), test present and !THP together.
704 */
705 pmde = *pmd;
706 barrier();
707 if (!pmd_present(pmde) || pmd_trans_huge(pmde))
708 pmd = NULL;
709out:
710 return pmd;
711}
712
713/*
714 * Check that @page is mapped at @address into @mm.
715 *
716 * If @sync is false, page_check_address may perform a racy check to avoid
717 * the page table lock when the pte is not present (helpful when reclaiming
718 * highly shared pages).
719 *
720 * On success returns with pte mapped and locked.
721 */
722pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
723 unsigned long address, spinlock_t **ptlp, int sync)
724{
725 pmd_t *pmd;
726 pte_t *pte;
727 spinlock_t *ptl;
728
729 if (unlikely(PageHuge(page))) {
730 /* when pud is not present, pte will be NULL */
731 pte = huge_pte_offset(mm, address);
732 if (!pte)
733 return NULL;
734
735 ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
736 goto check;
737 }
738
739 pmd = mm_find_pmd(mm, address);
740 if (!pmd)
741 return NULL;
742
743 pte = pte_offset_map(pmd, address);
744 /* Make a quick check before getting the lock */
745 if (!sync && !pte_present(*pte)) {
746 pte_unmap(pte);
747 return NULL;
748 }
749
750 ptl = pte_lockptr(mm, pmd);
751check:
752 spin_lock(ptl);
753 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
754 *ptlp = ptl;
755 return pte;
756 }
757 pte_unmap_unlock(pte, ptl);
758 return NULL;
759}
760
761/**
762 * page_mapped_in_vma - check whether a page is really mapped in a VMA
763 * @page: the page to test
764 * @vma: the VMA to test
765 *
766 * Returns 1 if the page is mapped into the page tables of the VMA, 0
767 * if the page is not mapped into the page tables of this VMA. Only
768 * valid for normal file or anonymous VMAs.
769 */
770int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
771{
772 unsigned long address;
773 pte_t *pte;
774 spinlock_t *ptl;
775
776 address = __vma_address(page, vma);
777 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
778 return 0;
779 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
780 if (!pte) /* the page is not in this mm */
781 return 0;
782 pte_unmap_unlock(pte, ptl);
783
784 return 1;
785}
786
787#ifdef CONFIG_TRANSPARENT_HUGEPAGE
788/*
789 * Check that @page is mapped at @address into @mm. In contrast to
790 * page_check_address(), this function can handle transparent huge pages.
791 *
792 * On success returns true with pte mapped and locked. For PMD-mapped
793 * transparent huge pages *@ptep is set to NULL.
794 */
795bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
796 unsigned long address, pmd_t **pmdp,
797 pte_t **ptep, spinlock_t **ptlp)
798{
799 pgd_t *pgd;
800 pud_t *pud;
801 pmd_t *pmd;
802 pte_t *pte;
803 spinlock_t *ptl;
804
805 if (unlikely(PageHuge(page))) {
806 /* when pud is not present, pte will be NULL */
807 pte = huge_pte_offset(mm, address);
808 if (!pte)
809 return false;
810
811 ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
812 pmd = NULL;
813 goto check_pte;
814 }
815
816 pgd = pgd_offset(mm, address);
817 if (!pgd_present(*pgd))
818 return false;
819 pud = pud_offset(pgd, address);
820 if (!pud_present(*pud))
821 return false;
822 pmd = pmd_offset(pud, address);
823
824 if (pmd_trans_huge(*pmd)) {
825 ptl = pmd_lock(mm, pmd);
826 if (!pmd_present(*pmd))
827 goto unlock_pmd;
828 if (unlikely(!pmd_trans_huge(*pmd))) {
829 spin_unlock(ptl);
830 goto map_pte;
831 }
832
833 if (pmd_page(*pmd) != page)
834 goto unlock_pmd;
835
836 pte = NULL;
837 goto found;
838unlock_pmd:
839 spin_unlock(ptl);
840 return false;
841 } else {
842 pmd_t pmde = *pmd;
843
844 barrier();
845 if (!pmd_present(pmde) || pmd_trans_huge(pmde))
846 return false;
847 }
848map_pte:
849 pte = pte_offset_map(pmd, address);
850 if (!pte_present(*pte)) {
851 pte_unmap(pte);
852 return false;
853 }
854
855 ptl = pte_lockptr(mm, pmd);
856check_pte:
857 spin_lock(ptl);
858
859 if (!pte_present(*pte)) {
860 pte_unmap_unlock(pte, ptl);
861 return false;
862 }
863
864 /* THP can be referenced by any subpage */
865 if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) {
866 pte_unmap_unlock(pte, ptl);
867 return false;
868 }
869found:
870 *ptep = pte;
871 *pmdp = pmd;
872 *ptlp = ptl;
873 return true;
874}
875#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
876
877struct page_referenced_arg {
878 int mapcount;
879 int referenced;
880 unsigned long vm_flags;
881 struct mem_cgroup *memcg;
882};
883/*
884 * arg: page_referenced_arg will be passed
885 */
886static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
887 unsigned long address, void *arg)
888{
889 struct mm_struct *mm = vma->vm_mm;
890 struct page_referenced_arg *pra = arg;
891 pmd_t *pmd;
892 pte_t *pte;
893 spinlock_t *ptl;
894 int referenced = 0;
895
896 if (!page_check_address_transhuge(page, mm, address, &pmd, &pte, &ptl))
897 return SWAP_AGAIN;
898
899 if (vma->vm_flags & VM_LOCKED) {
900 if (pte)
901 pte_unmap(pte);
902 spin_unlock(ptl);
903 pra->vm_flags |= VM_LOCKED;
904 return SWAP_FAIL; /* To break the loop */
905 }
906
907 if (pte) {
908 if (ptep_clear_flush_young_notify(vma, address, pte)) {
909 /*
910 * Don't treat a reference through a sequentially read
911 * mapping as such. If the page has been used in
912 * another mapping, we will catch it; if this other
913 * mapping is already gone, the unmap path will have
914 * set PG_referenced or activated the page.
915 */
916 if (likely(!(vma->vm_flags & VM_SEQ_READ)))
917 referenced++;
918 }
919 pte_unmap(pte);
920 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
921 if (pmdp_clear_flush_young_notify(vma, address, pmd))
922 referenced++;
923 } else {
924 /* unexpected pmd-mapped page? */
925 WARN_ON_ONCE(1);
926 }
927 spin_unlock(ptl);
928
929 if (referenced)
930 clear_page_idle(page);
931 if (test_and_clear_page_young(page))
932 referenced++;
933
934 if (referenced) {
935 pra->referenced++;
936 pra->vm_flags |= vma->vm_flags;
937 }
938
939 pra->mapcount--;
940 if (!pra->mapcount)
941 return SWAP_SUCCESS; /* To break the loop */
942
943 return SWAP_AGAIN;
944}
945
946static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
947{
948 struct page_referenced_arg *pra = arg;
949 struct mem_cgroup *memcg = pra->memcg;
950
951 if (!mm_match_cgroup(vma->vm_mm, memcg))
952 return true;
953
954 return false;
955}
956
957/**
958 * page_referenced - test if the page was referenced
959 * @page: the page to test
960 * @is_locked: caller holds lock on the page
961 * @memcg: target memory cgroup
962 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
963 *
964 * Quick test_and_clear_referenced for all mappings to a page,
965 * returns the number of ptes which referenced the page.
966 */
967int page_referenced(struct page *page,
968 int is_locked,
969 struct mem_cgroup *memcg,
970 unsigned long *vm_flags)
971{
972 int ret;
973 int we_locked = 0;
974 struct page_referenced_arg pra = {
975 .mapcount = total_mapcount(page),
976 .memcg = memcg,
977 };
978 struct rmap_walk_control rwc = {
979 .rmap_one = page_referenced_one,
980 .arg = (void *)&pra,
981 .anon_lock = page_lock_anon_vma_read,
982 };
983
984 *vm_flags = 0;
985 if (!page_mapped(page))
986 return 0;
987
988 if (!page_rmapping(page))
989 return 0;
990
991 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
992 we_locked = trylock_page(page);
993 if (!we_locked)
994 return 1;
995 }
996
997 /*
998 * If we are reclaiming on behalf of a cgroup, skip
999 * counting on behalf of references from different
1000 * cgroups
1001 */
1002 if (memcg) {
1003 rwc.invalid_vma = invalid_page_referenced_vma;
1004 }
1005
1006 ret = rmap_walk(page, &rwc);
1007 *vm_flags = pra.vm_flags;
1008
1009 if (we_locked)
1010 unlock_page(page);
1011
1012 return pra.referenced;
1013}
1014
1015static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
1016 unsigned long address, void *arg)
1017{
1018 struct mm_struct *mm = vma->vm_mm;
1019 pte_t *pte;
1020 spinlock_t *ptl;
1021 int ret = 0;
1022 int *cleaned = arg;
1023
1024 pte = page_check_address(page, mm, address, &ptl, 1);
1025 if (!pte)
1026 goto out;
1027
1028 if (pte_dirty(*pte) || pte_write(*pte)) {
1029 pte_t entry;
1030
1031 flush_cache_page(vma, address, pte_pfn(*pte));
1032 entry = ptep_clear_flush(vma, address, pte);
1033 entry = pte_wrprotect(entry);
1034 entry = pte_mkclean(entry);
1035 set_pte_at(mm, address, pte, entry);
1036 ret = 1;
1037 }
1038
1039 pte_unmap_unlock(pte, ptl);
1040
1041 if (ret) {
1042 mmu_notifier_invalidate_page(mm, address);
1043 (*cleaned)++;
1044 }
1045out:
1046 return SWAP_AGAIN;
1047}
1048
1049static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
1050{
1051 if (vma->vm_flags & VM_SHARED)
1052 return false;
1053
1054 return true;
1055}
1056
1057int page_mkclean(struct page *page)
1058{
1059 int cleaned = 0;
1060 struct address_space *mapping;
1061 struct rmap_walk_control rwc = {
1062 .arg = (void *)&cleaned,
1063 .rmap_one = page_mkclean_one,
1064 .invalid_vma = invalid_mkclean_vma,
1065 };
1066
1067 BUG_ON(!PageLocked(page));
1068
1069 if (!page_mapped(page))
1070 return 0;
1071
1072 mapping = page_mapping(page);
1073 if (!mapping)
1074 return 0;
1075
1076 rmap_walk(page, &rwc);
1077
1078 return cleaned;
1079}
1080EXPORT_SYMBOL_GPL(page_mkclean);
1081
1082/**
1083 * page_move_anon_rmap - move a page to our anon_vma
1084 * @page: the page to move to our anon_vma
1085 * @vma: the vma the page belongs to
1086 *
1087 * When a page belongs exclusively to one process after a COW event,
1088 * that page can be moved into the anon_vma that belongs to just that
1089 * process, so the rmap code will not search the parent or sibling
1090 * processes.
1091 */
1092void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
1093{
1094 struct anon_vma *anon_vma = vma->anon_vma;
1095
1096 page = compound_head(page);
1097
1098 VM_BUG_ON_PAGE(!PageLocked(page), page);
1099 VM_BUG_ON_VMA(!anon_vma, vma);
1100
1101 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1102 /*
1103 * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
1104 * simultaneously, so a concurrent reader (eg page_referenced()'s
1105 * PageAnon()) will not see one without the other.
1106 */
1107 WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
1108}
1109
1110/**
1111 * __page_set_anon_rmap - set up new anonymous rmap
1112 * @page: Page to add to rmap
1113 * @vma: VM area to add page to.
1114 * @address: User virtual address of the mapping
1115 * @exclusive: the page is exclusively owned by the current process
1116 */
1117static void __page_set_anon_rmap(struct page *page,
1118 struct vm_area_struct *vma, unsigned long address, int exclusive)
1119{
1120 struct anon_vma *anon_vma = vma->anon_vma;
1121
1122 BUG_ON(!anon_vma);
1123
1124 if (PageAnon(page))
1125 return;
1126
1127 /*
1128 * If the page isn't exclusively mapped into this vma,
1129 * we must use the _oldest_ possible anon_vma for the
1130 * page mapping!
1131 */
1132 if (!exclusive)
1133 anon_vma = anon_vma->root;
1134
1135 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1136 page->mapping = (struct address_space *) anon_vma;
1137 page->index = linear_page_index(vma, address);
1138}
1139
1140/**
1141 * __page_check_anon_rmap - sanity check anonymous rmap addition
1142 * @page: the page to add the mapping to
1143 * @vma: the vm area in which the mapping is added
1144 * @address: the user virtual address mapped
1145 */
1146static void __page_check_anon_rmap(struct page *page,
1147 struct vm_area_struct *vma, unsigned long address)
1148{
1149#ifdef CONFIG_DEBUG_VM
1150 /*
1151 * The page's anon-rmap details (mapping and index) are guaranteed to
1152 * be set up correctly at this point.
1153 *
1154 * We have exclusion against page_add_anon_rmap because the caller
1155 * always holds the page locked, except if called from page_dup_rmap,
1156 * in which case the page is already known to be setup.
1157 *
1158 * We have exclusion against page_add_new_anon_rmap because those pages
1159 * are initially only visible via the pagetables, and the pte is locked
1160 * over the call to page_add_new_anon_rmap.
1161 */
1162 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
1163 BUG_ON(page_to_pgoff(page) != linear_page_index(vma, address));
1164#endif
1165}
1166
1167/**
1168 * page_add_anon_rmap - add pte mapping to an anonymous page
1169 * @page: the page to add the mapping to
1170 * @vma: the vm area in which the mapping is added
1171 * @address: the user virtual address mapped
1172 * @compound: charge the page as compound or small page
1173 *
1174 * The caller needs to hold the pte lock, and the page must be locked in
1175 * the anon_vma case: to serialize mapping,index checking after setting,
1176 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1177 * (but PageKsm is never downgraded to PageAnon).
1178 */
1179void page_add_anon_rmap(struct page *page,
1180 struct vm_area_struct *vma, unsigned long address, bool compound)
1181{
1182 do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0);
1183}
1184
1185/*
1186 * Special version of the above for do_swap_page, which often runs
1187 * into pages that are exclusively owned by the current process.
1188 * Everybody else should continue to use page_add_anon_rmap above.
1189 */
1190void do_page_add_anon_rmap(struct page *page,
1191 struct vm_area_struct *vma, unsigned long address, int flags)
1192{
1193 bool compound = flags & RMAP_COMPOUND;
1194 bool first;
1195
1196 if (compound) {
1197 atomic_t *mapcount;
1198 VM_BUG_ON_PAGE(!PageLocked(page), page);
1199 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
1200 mapcount = compound_mapcount_ptr(page);
1201 first = atomic_inc_and_test(mapcount);
1202 } else {
1203 first = atomic_inc_and_test(&page->_mapcount);
1204 }
1205
1206 if (first) {
1207 int nr = compound ? hpage_nr_pages(page) : 1;
1208 /*
1209 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1210 * these counters are not modified in interrupt context, and
1211 * pte lock(a spinlock) is held, which implies preemption
1212 * disabled.
1213 */
1214 if (compound)
1215 __inc_node_page_state(page, NR_ANON_THPS);
1216 __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
1217 }
1218 if (unlikely(PageKsm(page)))
1219 return;
1220
1221 VM_BUG_ON_PAGE(!PageLocked(page), page);
1222
1223 /* address might be in next vma when migration races vma_adjust */
1224 if (first)
1225 __page_set_anon_rmap(page, vma, address,
1226 flags & RMAP_EXCLUSIVE);
1227 else
1228 __page_check_anon_rmap(page, vma, address);
1229}
1230
1231/**
1232 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1233 * @page: the page to add the mapping to
1234 * @vma: the vm area in which the mapping is added
1235 * @address: the user virtual address mapped
1236 * @compound: charge the page as compound or small page
1237 *
1238 * Same as page_add_anon_rmap but must only be called on *new* pages.
1239 * This means the inc-and-test can be bypassed.
1240 * Page does not have to be locked.
1241 */
1242void page_add_new_anon_rmap(struct page *page,
1243 struct vm_area_struct *vma, unsigned long address, bool compound)
1244{
1245 int nr = compound ? hpage_nr_pages(page) : 1;
1246
1247 VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
1248 __SetPageSwapBacked(page);
1249 if (compound) {
1250 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
1251 /* increment count (starts at -1) */
1252 atomic_set(compound_mapcount_ptr(page), 0);
1253 __inc_node_page_state(page, NR_ANON_THPS);
1254 } else {
1255 /* Anon THP always mapped first with PMD */
1256 VM_BUG_ON_PAGE(PageTransCompound(page), page);
1257 /* increment count (starts at -1) */
1258 atomic_set(&page->_mapcount, 0);
1259 }
1260 __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
1261 __page_set_anon_rmap(page, vma, address, 1);
1262}
1263
1264/**
1265 * page_add_file_rmap - add pte mapping to a file page
1266 * @page: the page to add the mapping to
1267 *
1268 * The caller needs to hold the pte lock.
1269 */
1270void page_add_file_rmap(struct page *page, bool compound)
1271{
1272 int i, nr = 1;
1273
1274 VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
1275 lock_page_memcg(page);
1276 if (compound && PageTransHuge(page)) {
1277 for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1278 if (atomic_inc_and_test(&page[i]._mapcount))
1279 nr++;
1280 }
1281 if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
1282 goto out;
1283 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
1284 __inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
1285 } else {
1286 if (PageTransCompound(page) && page_mapping(page)) {
1287 VM_WARN_ON_ONCE(!PageLocked(page));
1288
1289 SetPageDoubleMap(compound_head(page));
1290 if (PageMlocked(page))
1291 clear_page_mlock(compound_head(page));
1292 }
1293 if (!atomic_inc_and_test(&page->_mapcount))
1294 goto out;
1295 }
1296 __mod_node_page_state(page_pgdat(page), NR_FILE_MAPPED, nr);
1297 mem_cgroup_update_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED, nr);
1298out:
1299 unlock_page_memcg(page);
1300}
1301
1302static void page_remove_file_rmap(struct page *page, bool compound)
1303{
1304 int i, nr = 1;
1305
1306 VM_BUG_ON_PAGE(compound && !PageHead(page), page);
1307 lock_page_memcg(page);
1308
1309 /* Hugepages are not counted in NR_FILE_MAPPED for now. */
1310 if (unlikely(PageHuge(page))) {
1311 /* hugetlb pages are always mapped with pmds */
1312 atomic_dec(compound_mapcount_ptr(page));
1313 goto out;
1314 }
1315
1316 /* page still mapped by someone else? */
1317 if (compound && PageTransHuge(page)) {
1318 for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1319 if (atomic_add_negative(-1, &page[i]._mapcount))
1320 nr++;
1321 }
1322 if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
1323 goto out;
1324 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
1325 __dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
1326 } else {
1327 if (!atomic_add_negative(-1, &page->_mapcount))
1328 goto out;
1329 }
1330
1331 /*
1332 * We use the irq-unsafe __{inc|mod}_zone_page_state because
1333 * these counters are not modified in interrupt context, and
1334 * pte lock(a spinlock) is held, which implies preemption disabled.
1335 */
1336 __mod_node_page_state(page_pgdat(page), NR_FILE_MAPPED, -nr);
1337 mem_cgroup_update_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED, -nr);
1338
1339 if (unlikely(PageMlocked(page)))
1340 clear_page_mlock(page);
1341out:
1342 unlock_page_memcg(page);
1343}
1344
1345static void page_remove_anon_compound_rmap(struct page *page)
1346{
1347 int i, nr;
1348
1349 if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
1350 return;
1351
1352 /* Hugepages are not counted in NR_ANON_PAGES for now. */
1353 if (unlikely(PageHuge(page)))
1354 return;
1355
1356 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1357 return;
1358
1359 __dec_node_page_state(page, NR_ANON_THPS);
1360
1361 if (TestClearPageDoubleMap(page)) {
1362 /*
1363 * Subpages can be mapped with PTEs too. Check how many of
1364 * themi are still mapped.
1365 */
1366 for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1367 if (atomic_add_negative(-1, &page[i]._mapcount))
1368 nr++;
1369 }
1370 } else {
1371 nr = HPAGE_PMD_NR;
1372 }
1373
1374 if (unlikely(PageMlocked(page)))
1375 clear_page_mlock(page);
1376
1377 if (nr) {
1378 __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
1379 deferred_split_huge_page(page);
1380 }
1381}
1382
1383/**
1384 * page_remove_rmap - take down pte mapping from a page
1385 * @page: page to remove mapping from
1386 * @compound: uncharge the page as compound or small page
1387 *
1388 * The caller needs to hold the pte lock.
1389 */
1390void page_remove_rmap(struct page *page, bool compound)
1391{
1392 if (!PageAnon(page))
1393 return page_remove_file_rmap(page, compound);
1394
1395 if (compound)
1396 return page_remove_anon_compound_rmap(page);
1397
1398 /* page still mapped by someone else? */
1399 if (!atomic_add_negative(-1, &page->_mapcount))
1400 return;
1401
1402 /*
1403 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1404 * these counters are not modified in interrupt context, and
1405 * pte lock(a spinlock) is held, which implies preemption disabled.
1406 */
1407 __dec_node_page_state(page, NR_ANON_MAPPED);
1408
1409 if (unlikely(PageMlocked(page)))
1410 clear_page_mlock(page);
1411
1412 if (PageTransCompound(page))
1413 deferred_split_huge_page(compound_head(page));
1414
1415 /*
1416 * It would be tidy to reset the PageAnon mapping here,
1417 * but that might overwrite a racing page_add_anon_rmap
1418 * which increments mapcount after us but sets mapping
1419 * before us: so leave the reset to free_hot_cold_page,
1420 * and remember that it's only reliable while mapped.
1421 * Leaving it set also helps swapoff to reinstate ptes
1422 * faster for those pages still in swapcache.
1423 */
1424}
1425
1426struct rmap_private {
1427 enum ttu_flags flags;
1428 int lazyfreed;
1429};
1430
1431/*
1432 * @arg: enum ttu_flags will be passed to this argument
1433 */
1434static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1435 unsigned long address, void *arg)
1436{
1437 struct mm_struct *mm = vma->vm_mm;
1438 pte_t *pte;
1439 pte_t pteval;
1440 spinlock_t *ptl;
1441 int ret = SWAP_AGAIN;
1442 struct rmap_private *rp = arg;
1443 enum ttu_flags flags = rp->flags;
1444
1445 /* munlock has nothing to gain from examining un-locked vmas */
1446 if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
1447 goto out;
1448
1449 if (flags & TTU_SPLIT_HUGE_PMD) {
1450 split_huge_pmd_address(vma, address,
1451 flags & TTU_MIGRATION, page);
1452 /* check if we have anything to do after split */
1453 if (page_mapcount(page) == 0)
1454 goto out;
1455 }
1456
1457 pte = page_check_address(page, mm, address, &ptl,
1458 PageTransCompound(page));
1459 if (!pte)
1460 goto out;
1461
1462 /*
1463 * If the page is mlock()d, we cannot swap it out.
1464 * If it's recently referenced (perhaps page_referenced
1465 * skipped over this mm) then we should reactivate it.
1466 */
1467 if (!(flags & TTU_IGNORE_MLOCK)) {
1468 if (vma->vm_flags & VM_LOCKED) {
1469 /* PTE-mapped THP are never mlocked */
1470 if (!PageTransCompound(page)) {
1471 /*
1472 * Holding pte lock, we do *not* need
1473 * mmap_sem here
1474 */
1475 mlock_vma_page(page);
1476 }
1477 ret = SWAP_MLOCK;
1478 goto out_unmap;
1479 }
1480 if (flags & TTU_MUNLOCK)
1481 goto out_unmap;
1482 }
1483 if (!(flags & TTU_IGNORE_ACCESS)) {
1484 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1485 ret = SWAP_FAIL;
1486 goto out_unmap;
1487 }
1488 }
1489
1490 /* Nuke the page table entry. */
1491 flush_cache_page(vma, address, page_to_pfn(page));
1492 if (should_defer_flush(mm, flags)) {
1493 /*
1494 * We clear the PTE but do not flush so potentially a remote
1495 * CPU could still be writing to the page. If the entry was
1496 * previously clean then the architecture must guarantee that
1497 * a clear->dirty transition on a cached TLB entry is written
1498 * through and traps if the PTE is unmapped.
1499 */
1500 pteval = ptep_get_and_clear(mm, address, pte);
1501
1502 set_tlb_ubc_flush_pending(mm, page, pte_dirty(pteval));
1503 } else {
1504 pteval = ptep_clear_flush(vma, address, pte);
1505 }
1506
1507 /* Move the dirty bit to the physical page now the pte is gone. */
1508 if (pte_dirty(pteval))
1509 set_page_dirty(page);
1510
1511 /* Update high watermark before we lower rss */
1512 update_hiwater_rss(mm);
1513
1514 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
1515 if (PageHuge(page)) {
1516 hugetlb_count_sub(1 << compound_order(page), mm);
1517 } else {
1518 dec_mm_counter(mm, mm_counter(page));
1519 }
1520 set_pte_at(mm, address, pte,
1521 swp_entry_to_pte(make_hwpoison_entry(page)));
1522 } else if (pte_unused(pteval)) {
1523 /*
1524 * The guest indicated that the page content is of no
1525 * interest anymore. Simply discard the pte, vmscan
1526 * will take care of the rest.
1527 */
1528 dec_mm_counter(mm, mm_counter(page));
1529 } else if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION)) {
1530 swp_entry_t entry;
1531 pte_t swp_pte;
1532 /*
1533 * Store the pfn of the page in a special migration
1534 * pte. do_swap_page() will wait until the migration
1535 * pte is removed and then restart fault handling.
1536 */
1537 entry = make_migration_entry(page, pte_write(pteval));
1538 swp_pte = swp_entry_to_pte(entry);
1539 if (pte_soft_dirty(pteval))
1540 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1541 set_pte_at(mm, address, pte, swp_pte);
1542 } else if (PageAnon(page)) {
1543 swp_entry_t entry = { .val = page_private(page) };
1544 pte_t swp_pte;
1545 /*
1546 * Store the swap location in the pte.
1547 * See handle_pte_fault() ...
1548 */
1549 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
1550
1551 if (!PageDirty(page) && (flags & TTU_LZFREE)) {
1552 /* It's a freeable page by MADV_FREE */
1553 dec_mm_counter(mm, MM_ANONPAGES);
1554 rp->lazyfreed++;
1555 goto discard;
1556 }
1557
1558 if (swap_duplicate(entry) < 0) {
1559 set_pte_at(mm, address, pte, pteval);
1560 ret = SWAP_FAIL;
1561 goto out_unmap;
1562 }
1563 if (list_empty(&mm->mmlist)) {
1564 spin_lock(&mmlist_lock);
1565 if (list_empty(&mm->mmlist))
1566 list_add(&mm->mmlist, &init_mm.mmlist);
1567 spin_unlock(&mmlist_lock);
1568 }
1569 dec_mm_counter(mm, MM_ANONPAGES);
1570 inc_mm_counter(mm, MM_SWAPENTS);
1571 swp_pte = swp_entry_to_pte(entry);
1572 if (pte_soft_dirty(pteval))
1573 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1574 set_pte_at(mm, address, pte, swp_pte);
1575 } else
1576 dec_mm_counter(mm, mm_counter_file(page));
1577
1578discard:
1579 page_remove_rmap(page, PageHuge(page));
1580 put_page(page);
1581
1582out_unmap:
1583 pte_unmap_unlock(pte, ptl);
1584 if (ret != SWAP_FAIL && ret != SWAP_MLOCK && !(flags & TTU_MUNLOCK))
1585 mmu_notifier_invalidate_page(mm, address);
1586out:
1587 return ret;
1588}
1589
1590bool is_vma_temporary_stack(struct vm_area_struct *vma)
1591{
1592 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1593
1594 if (!maybe_stack)
1595 return false;
1596
1597 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1598 VM_STACK_INCOMPLETE_SETUP)
1599 return true;
1600
1601 return false;
1602}
1603
1604static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
1605{
1606 return is_vma_temporary_stack(vma);
1607}
1608
1609static int page_mapcount_is_zero(struct page *page)
1610{
1611 return !page_mapcount(page);
1612}
1613
1614/**
1615 * try_to_unmap - try to remove all page table mappings to a page
1616 * @page: the page to get unmapped
1617 * @flags: action and flags
1618 *
1619 * Tries to remove all the page table entries which are mapping this
1620 * page, used in the pageout path. Caller must hold the page lock.
1621 * Return values are:
1622 *
1623 * SWAP_SUCCESS - we succeeded in removing all mappings
1624 * SWAP_AGAIN - we missed a mapping, try again later
1625 * SWAP_FAIL - the page is unswappable
1626 * SWAP_MLOCK - page is mlocked.
1627 */
1628int try_to_unmap(struct page *page, enum ttu_flags flags)
1629{
1630 int ret;
1631 struct rmap_private rp = {
1632 .flags = flags,
1633 .lazyfreed = 0,
1634 };
1635
1636 struct rmap_walk_control rwc = {
1637 .rmap_one = try_to_unmap_one,
1638 .arg = &rp,
1639 .done = page_mapcount_is_zero,
1640 .anon_lock = page_lock_anon_vma_read,
1641 };
1642
1643 /*
1644 * During exec, a temporary VMA is setup and later moved.
1645 * The VMA is moved under the anon_vma lock but not the
1646 * page tables leading to a race where migration cannot
1647 * find the migration ptes. Rather than increasing the
1648 * locking requirements of exec(), migration skips
1649 * temporary VMAs until after exec() completes.
1650 */
1651 if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
1652 rwc.invalid_vma = invalid_migration_vma;
1653
1654 if (flags & TTU_RMAP_LOCKED)
1655 ret = rmap_walk_locked(page, &rwc);
1656 else
1657 ret = rmap_walk(page, &rwc);
1658
1659 if (ret != SWAP_MLOCK && !page_mapcount(page)) {
1660 ret = SWAP_SUCCESS;
1661 if (rp.lazyfreed && !PageDirty(page))
1662 ret = SWAP_LZFREE;
1663 }
1664 return ret;
1665}
1666
1667static int page_not_mapped(struct page *page)
1668{
1669 return !page_mapped(page);
1670};
1671
1672/**
1673 * try_to_munlock - try to munlock a page
1674 * @page: the page to be munlocked
1675 *
1676 * Called from munlock code. Checks all of the VMAs mapping the page
1677 * to make sure nobody else has this page mlocked. The page will be
1678 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1679 *
1680 * Return values are:
1681 *
1682 * SWAP_AGAIN - no vma is holding page mlocked, or,
1683 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
1684 * SWAP_FAIL - page cannot be located at present
1685 * SWAP_MLOCK - page is now mlocked.
1686 */
1687int try_to_munlock(struct page *page)
1688{
1689 int ret;
1690 struct rmap_private rp = {
1691 .flags = TTU_MUNLOCK,
1692 .lazyfreed = 0,
1693 };
1694
1695 struct rmap_walk_control rwc = {
1696 .rmap_one = try_to_unmap_one,
1697 .arg = &rp,
1698 .done = page_not_mapped,
1699 .anon_lock = page_lock_anon_vma_read,
1700
1701 };
1702
1703 VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
1704
1705 ret = rmap_walk(page, &rwc);
1706 return ret;
1707}
1708
1709void __put_anon_vma(struct anon_vma *anon_vma)
1710{
1711 struct anon_vma *root = anon_vma->root;
1712
1713 anon_vma_free(anon_vma);
1714 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1715 anon_vma_free(root);
1716}
1717
1718static struct anon_vma *rmap_walk_anon_lock(struct page *page,
1719 struct rmap_walk_control *rwc)
1720{
1721 struct anon_vma *anon_vma;
1722
1723 if (rwc->anon_lock)
1724 return rwc->anon_lock(page);
1725
1726 /*
1727 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
1728 * because that depends on page_mapped(); but not all its usages
1729 * are holding mmap_sem. Users without mmap_sem are required to
1730 * take a reference count to prevent the anon_vma disappearing
1731 */
1732 anon_vma = page_anon_vma(page);
1733 if (!anon_vma)
1734 return NULL;
1735
1736 anon_vma_lock_read(anon_vma);
1737 return anon_vma;
1738}
1739
1740/*
1741 * rmap_walk_anon - do something to anonymous page using the object-based
1742 * rmap method
1743 * @page: the page to be handled
1744 * @rwc: control variable according to each walk type
1745 *
1746 * Find all the mappings of a page using the mapping pointer and the vma chains
1747 * contained in the anon_vma struct it points to.
1748 *
1749 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1750 * where the page was found will be held for write. So, we won't recheck
1751 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1752 * LOCKED.
1753 */
1754static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
1755 bool locked)
1756{
1757 struct anon_vma *anon_vma;
1758 pgoff_t pgoff;
1759 struct anon_vma_chain *avc;
1760 int ret = SWAP_AGAIN;
1761
1762 if (locked) {
1763 anon_vma = page_anon_vma(page);
1764 /* anon_vma disappear under us? */
1765 VM_BUG_ON_PAGE(!anon_vma, page);
1766 } else {
1767 anon_vma = rmap_walk_anon_lock(page, rwc);
1768 }
1769 if (!anon_vma)
1770 return ret;
1771
1772 pgoff = page_to_pgoff(page);
1773 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1774 struct vm_area_struct *vma = avc->vma;
1775 unsigned long address = vma_address(page, vma);
1776
1777 cond_resched();
1778
1779 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1780 continue;
1781
1782 ret = rwc->rmap_one(page, vma, address, rwc->arg);
1783 if (ret != SWAP_AGAIN)
1784 break;
1785 if (rwc->done && rwc->done(page))
1786 break;
1787 }
1788
1789 if (!locked)
1790 anon_vma_unlock_read(anon_vma);
1791 return ret;
1792}
1793
1794/*
1795 * rmap_walk_file - do something to file page using the object-based rmap method
1796 * @page: the page to be handled
1797 * @rwc: control variable according to each walk type
1798 *
1799 * Find all the mappings of a page using the mapping pointer and the vma chains
1800 * contained in the address_space struct it points to.
1801 *
1802 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1803 * where the page was found will be held for write. So, we won't recheck
1804 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1805 * LOCKED.
1806 */
1807static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
1808 bool locked)
1809{
1810 struct address_space *mapping = page_mapping(page);
1811 pgoff_t pgoff;
1812 struct vm_area_struct *vma;
1813 int ret = SWAP_AGAIN;
1814
1815 /*
1816 * The page lock not only makes sure that page->mapping cannot
1817 * suddenly be NULLified by truncation, it makes sure that the
1818 * structure at mapping cannot be freed and reused yet,
1819 * so we can safely take mapping->i_mmap_rwsem.
1820 */
1821 VM_BUG_ON_PAGE(!PageLocked(page), page);
1822
1823 if (!mapping)
1824 return ret;
1825
1826 pgoff = page_to_pgoff(page);
1827 if (!locked)
1828 i_mmap_lock_read(mapping);
1829 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
1830 unsigned long address = vma_address(page, vma);
1831
1832 cond_resched();
1833
1834 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1835 continue;
1836
1837 ret = rwc->rmap_one(page, vma, address, rwc->arg);
1838 if (ret != SWAP_AGAIN)
1839 goto done;
1840 if (rwc->done && rwc->done(page))
1841 goto done;
1842 }
1843
1844done:
1845 if (!locked)
1846 i_mmap_unlock_read(mapping);
1847 return ret;
1848}
1849
1850int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
1851{
1852 if (unlikely(PageKsm(page)))
1853 return rmap_walk_ksm(page, rwc);
1854 else if (PageAnon(page))
1855 return rmap_walk_anon(page, rwc, false);
1856 else
1857 return rmap_walk_file(page, rwc, false);
1858}
1859
1860/* Like rmap_walk, but caller holds relevant rmap lock */
1861int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc)
1862{
1863 /* no ksm support for now */
1864 VM_BUG_ON_PAGE(PageKsm(page), page);
1865 if (PageAnon(page))
1866 return rmap_walk_anon(page, rwc, true);
1867 else
1868 return rmap_walk_file(page, rwc, true);
1869}
1870
1871#ifdef CONFIG_HUGETLB_PAGE
1872/*
1873 * The following three functions are for anonymous (private mapped) hugepages.
1874 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1875 * and no lru code, because we handle hugepages differently from common pages.
1876 */
1877static void __hugepage_set_anon_rmap(struct page *page,
1878 struct vm_area_struct *vma, unsigned long address, int exclusive)
1879{
1880 struct anon_vma *anon_vma = vma->anon_vma;
1881
1882 BUG_ON(!anon_vma);
1883
1884 if (PageAnon(page))
1885 return;
1886 if (!exclusive)
1887 anon_vma = anon_vma->root;
1888
1889 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1890 page->mapping = (struct address_space *) anon_vma;
1891 page->index = linear_page_index(vma, address);
1892}
1893
1894void hugepage_add_anon_rmap(struct page *page,
1895 struct vm_area_struct *vma, unsigned long address)
1896{
1897 struct anon_vma *anon_vma = vma->anon_vma;
1898 int first;
1899
1900 BUG_ON(!PageLocked(page));
1901 BUG_ON(!anon_vma);
1902 /* address might be in next vma when migration races vma_adjust */
1903 first = atomic_inc_and_test(compound_mapcount_ptr(page));
1904 if (first)
1905 __hugepage_set_anon_rmap(page, vma, address, 0);
1906}
1907
1908void hugepage_add_new_anon_rmap(struct page *page,
1909 struct vm_area_struct *vma, unsigned long address)
1910{
1911 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1912 atomic_set(compound_mapcount_ptr(page), 0);
1913 __hugepage_set_anon_rmap(page, vma, address, 1);
1914}
1915#endif /* CONFIG_HUGETLB_PAGE */